Merge "SurfaceFlinger: decouple EventThread from SF wakeup"
diff --git a/cmds/surfacereplayer/replayer/Replayer.cpp b/cmds/surfacereplayer/replayer/Replayer.cpp
index 2b5667d..86e4f5d 100644
--- a/cmds/surfacereplayer/replayer/Replayer.cpp
+++ b/cmds/surfacereplayer/replayer/Replayer.cpp
@@ -584,9 +584,7 @@
         return;
     }
 
-    auto handle = mLayers[dtc.layer_id()]->getHandle();
-
-    t.deferTransactionUntil_legacy(mLayers[id], handle, dtc.frame_number());
+    t.deferTransactionUntil_legacy(mLayers[id], mLayers[dtc.layer_id()], dtc.frame_number());
 }
 
 void Replayer::setDisplaySurface(SurfaceComposerClient::Transaction& t,
@@ -706,11 +704,11 @@
 
 void Replayer::setReparentChange(SurfaceComposerClient::Transaction& t,
         layer_id id, const ReparentChange& c) {
-    sp<IBinder> newParentHandle = nullptr;
+    sp<SurfaceControl> newSurfaceControl = nullptr;
     if (mLayers.count(c.parent_id()) != 0 && mLayers[c.parent_id()] != nullptr) {
-        newParentHandle = mLayers[c.parent_id()]->getHandle();
+        newSurfaceControl = mLayers[c.parent_id()];
     }
-    t.reparent(mLayers[id], newParentHandle);
+    t.reparent(mLayers[id], newSurfaceControl);
 }
 
 void Replayer::setRelativeParentChange(SurfaceComposerClient::Transaction& t,
@@ -719,7 +717,7 @@
         ALOGE("Layer %d not found in set relative parent transaction", c.relative_parent_id());
         return;
     }
-    t.setRelativeLayer(mLayers[id], mLayers[c.relative_parent_id()]->getHandle(), c.z());
+    t.setRelativeLayer(mLayers[id], mLayers[c.relative_parent_id()], c.z());
 }
 
 void Replayer::setDetachChildrenChange(SurfaceComposerClient::Transaction& t,
@@ -733,7 +731,7 @@
         ALOGE("Layer %d not found in reparent children transaction", c.parent_id());
         return;
     }
-    t.reparentChildren(mLayers[id], mLayers[c.parent_id()]->getHandle());
+    t.reparentChildren(mLayers[id], mLayers[c.parent_id()]);
 }
 
 void Replayer::setShadowRadiusChange(SurfaceComposerClient::Transaction& t,
diff --git a/include/binder/Enum.h b/include/binder/Enum.h
new file mode 100644
index 0000000..4c25654
--- /dev/null
+++ b/include/binder/Enum.h
@@ -0,0 +1,22 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#error Do not rely on global include files. All Android cc_* programs are given access to \
+    include_dirs for frameworks/native/include via global configuration, but this is legacy \
+    configuration. Instead, you should have a direct dependency on libbinder OR one of your \
+    dependencies should re-export libbinder headers with export_shared_lib_headers.
diff --git a/include/input/Flags.h b/include/input/Flags.h
index 4ad9056..072dd18 100644
--- a/include/input/Flags.h
+++ b/include/input/Flags.h
@@ -22,6 +22,7 @@
 #include <string>
 #include <type_traits>
 
+#include "NamedEnum.h"
 #include "utils/BitSet.h"
 
 #ifndef __UI_INPUT_FLAGS_H
@@ -30,38 +31,6 @@
 namespace android {
 
 namespace details {
-template <typename F, F V>
-constexpr std::optional<std::string_view> enum_value_name() {
-    // Should look something like (but all on one line):
-    //   std::optional<std::string_view>
-    //   android::details::enum_value_name()
-    //   [F = android::test::TestFlags, V = android::test::TestFlags::ONE]
-    std::string_view view = __PRETTY_FUNCTION__;
-    size_t templateStart = view.rfind("[");
-    size_t templateEnd = view.rfind("]");
-    if (templateStart == std::string::npos || templateEnd == std::string::npos) {
-        return std::nullopt;
-    }
-
-    // Extract the template parameters without the enclosing braces.
-    // Example (cont'd): F = android::test::TestFlags, V = android::test::TestFlags::ONE
-    view = view.substr(templateStart + 1, templateEnd - templateStart - 1);
-    size_t valStart = view.rfind("V = ");
-    if (valStart == std::string::npos) {
-        return std::nullopt;
-    }
-
-    // Example (cont'd): V = android::test::TestFlags::ONE
-    view = view.substr(valStart);
-    size_t nameStart = view.rfind("::");
-    if (nameStart == std::string::npos) {
-        return std::nullopt;
-    }
-
-    // Chop off the initial "::"
-    nameStart += 2;
-    return view.substr(nameStart);
-}
 
 template <typename F>
 inline constexpr auto flag_count = sizeof(F) * __CHAR_BIT__;
diff --git a/include/input/NamedEnum.h b/include/input/NamedEnum.h
new file mode 100644
index 0000000..42cfb12
--- /dev/null
+++ b/include/input/NamedEnum.h
@@ -0,0 +1,128 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <android-base/stringprintf.h>
+
+#include <array>
+#include <cstdint>
+#include <optional>
+#include <string>
+
+#ifndef __UI_INPUT_NAMEDENUM_H
+#define __UI_INPUT_NAMEDENUM_H
+
+namespace android {
+
+namespace details {
+template <typename E, E V>
+constexpr std::optional<std::string_view> enum_value_name() {
+    // Should look something like (but all on one line):
+    //   std::optional<std::string_view>
+    //   android::details::enum_value_name()
+    //   [E = android::test::TestEnums, V = android::test::TestEnums::ONE]
+    std::string_view view = __PRETTY_FUNCTION__;
+    size_t templateStart = view.rfind("[");
+    size_t templateEnd = view.rfind("]");
+    if (templateStart == std::string::npos || templateEnd == std::string::npos) {
+        return std::nullopt;
+    }
+
+    // Extract the template parameters without the enclosing braces.
+    // Example (cont'd): E = android::test::TestEnums, V = android::test::TestEnums::ONE
+    view = view.substr(templateStart + 1, templateEnd - templateStart - 1);
+    size_t valStart = view.rfind("V = ");
+    if (valStart == std::string::npos) {
+        return std::nullopt;
+    }
+
+    // Example (cont'd): V = android::test::TestEnums::ONE
+    view = view.substr(valStart);
+    size_t nameStart = view.rfind("::");
+    if (nameStart == std::string::npos) {
+        return std::nullopt;
+    }
+
+    // Chop off the initial "::"
+    nameStart += 2;
+    return view.substr(nameStart);
+}
+
+template <typename E, typename T, T... I>
+constexpr auto generate_enum_values(std::integer_sequence<T, I...> seq) {
+    constexpr size_t count = seq.size();
+
+    std::array<E, count> values{};
+    for (size_t i = 0, v = 0; v < count; ++i) {
+        values[v++] = static_cast<E>(T{0} + i);
+    }
+
+    return values;
+}
+
+template <typename E, std::size_t N>
+inline constexpr auto enum_values =
+        generate_enum_values<E>(std::make_integer_sequence<std::underlying_type_t<E>, N>{});
+
+template <typename E, std::size_t N, std::size_t... I>
+constexpr auto generate_enum_names(std::index_sequence<I...>) noexcept {
+    return std::array<std::optional<std::string_view>, sizeof...(I)>{
+            {enum_value_name<E, enum_values<E, N>[I]>()...}};
+}
+
+template <typename E, std::size_t N>
+inline constexpr auto enum_names = generate_enum_names<E, N>(std::make_index_sequence<N>{});
+
+} // namespace details
+
+class NamedEnum {
+public:
+    // By default allowed enum value range is 0 ~ 7.
+    template <typename E>
+    static constexpr size_t max = 8;
+
+    template <auto V>
+    static constexpr auto enum_name() {
+        using E = decltype(V);
+        return details::enum_value_name<E, V>();
+    }
+
+    template <typename E>
+    static constexpr std::optional<std::string_view> enum_name(E val) {
+        auto idx = static_cast<size_t>(val);
+        return idx < max<E> ? details::enum_names<E, max<E>>[idx] : std::nullopt;
+    }
+
+    // Helper function for parsing enum value to string.
+    // Example : enum class TestEnums { ZERO = 0x0 };
+    // NamedEnum::string(TestEnums::ZERO) returns string of "ZERO".
+    // Note the default maximum enum is 8, if the enum ID to be parsed if greater than 8 like 16,
+    // it should be declared to specialized the maximum enum by below:
+    // template <> constexpr size_t NamedEnum::max<TestEnums> = 16;
+    // If the enum class definition is sparse and contains enum values starting from a large value,
+    // Do not specialize it to a large number to avoid performance issues.
+    // The recommended maximum enum number to specialize is 64.
+    template <typename E>
+    static const std::string string(E val) {
+        std::string result;
+        std::optional<std::string_view> enumString = enum_name(val);
+        result += enumString ? enumString.value() : base::StringPrintf("0x%08x", val);
+        return result;
+    }
+};
+
+} // namespace android
+
+#endif // __UI_INPUT_NAMEDENUM_H
\ No newline at end of file
diff --git a/libs/binder/rust/src/binder.rs b/libs/binder/rust/src/binder.rs
index 81a5f02..6d0a369 100644
--- a/libs/binder/rust/src/binder.rs
+++ b/libs/binder/rust/src/binder.rs
@@ -532,7 +532,17 @@
             }
 
             fn on_transact(&self, code: $crate::TransactionCode, data: &$crate::Parcel, reply: &mut $crate::Parcel) -> $crate::Result<()> {
-                $on_transact(&*self.0, code, data, reply)
+                match $on_transact(&*self.0, code, data, reply) {
+                    // The C++ backend converts UNEXPECTED_NULL into an exception
+                    Err($crate::StatusCode::UNEXPECTED_NULL) => {
+                        let status = $crate::Status::new_exception(
+                            $crate::ExceptionCode::NULL_POINTER,
+                            None,
+                        );
+                        reply.write(&status)
+                    },
+                    result => result
+                }
             }
 
             fn get_class() -> $crate::InterfaceClass {
diff --git a/libs/binder/rust/src/proxy.rs b/libs/binder/rust/src/proxy.rs
index 82212d8..5002fc6 100644
--- a/libs/binder/rust/src/proxy.rs
+++ b/libs/binder/rust/src/proxy.rs
@@ -352,7 +352,10 @@
 
 impl Deserialize for SpIBinder {
     fn deserialize(parcel: &Parcel) -> Result<SpIBinder> {
-        parcel.read_binder().transpose().unwrap()
+        parcel
+            .read_binder()
+            .transpose()
+            .unwrap_or(Err(StatusCode::UNEXPECTED_NULL))
     }
 }
 
diff --git a/libs/gui/BLASTBufferQueue.cpp b/libs/gui/BLASTBufferQueue.cpp
index ba72f9b..cce434a 100644
--- a/libs/gui/BLASTBufferQueue.cpp
+++ b/libs/gui/BLASTBufferQueue.cpp
@@ -166,8 +166,8 @@
                                            const std::vector<SurfaceControlStats>& stats) {
     std::unique_lock _lock{mMutex};
     ATRACE_CALL();
-
     BQA_LOGV("transactionCallback");
+    mInitialCallbackReceived = true;
 
     if (!stats.empty()) {
         mTransformHint = stats[0].transformHint;
@@ -185,7 +185,7 @@
         if (!stats.empty()) {
             mPendingReleaseItem.releaseFence = stats[0].previousReleaseFence;
         } else {
-            ALOGE("Warning: no SurfaceControlStats returned in BLASTBufferQueue callback");
+            BQA_LOGE("Warning: no SurfaceControlStats returned in BLASTBufferQueue callback");
             mPendingReleaseItem.releaseFence = nullptr;
         }
         mBufferItemConsumer->releaseBuffer(mPendingReleaseItem.item,
@@ -198,7 +198,7 @@
     }
 
     if (mSubmitted.empty()) {
-        ALOGE("ERROR: callback with no corresponding submitted buffer item");
+        BQA_LOGE("ERROR: callback with no corresponding submitted buffer item");
     }
     mPendingReleaseItem.item = std::move(mSubmitted.front());
     mSubmitted.pop();
@@ -213,12 +213,18 @@
     ATRACE_CALL();
     BQA_LOGV("processNextBufferLocked useNextTransaction=%s", toString(useNextTransaction));
 
-    if (mNumFrameAvailable == 0 || mNumAcquired == MAX_ACQUIRED_BUFFERS + 1) {
+    // Wait to acquire a buffer if there are no frames available or we have acquired the maximum
+    // number of buffers.
+    // As a special case, we wait for the first callback before acquiring the second buffer so we
+    // can ensure the first buffer is presented if multiple buffers are queued in succession.
+    if (mNumFrameAvailable == 0 || mNumAcquired == MAX_ACQUIRED_BUFFERS + 1 ||
+        (!mInitialCallbackReceived && mNumAcquired == 1)) {
+        BQA_LOGV("processNextBufferLocked waiting for frame available or callback");
         return;
     }
 
     if (mSurfaceControl == nullptr) {
-        ALOGE("ERROR : surface control is null");
+        BQA_LOGE("ERROR : surface control is null");
         return;
     }
 
@@ -245,6 +251,13 @@
         return;
     }
 
+    if (rejectBuffer(bufferItem)) {
+        BQA_LOGE("rejecting buffer: configured width=%d, height=%d, buffer{w=%d, h=%d}", mWidth,
+                 mHeight, buffer->getWidth(), buffer->getHeight());
+        mBufferItemConsumer->releaseBuffer(bufferItem, Fence::NO_FENCE);
+        return;
+    }
+
     mNumAcquired++;
     mSubmitted.push(bufferItem);
 
@@ -311,4 +324,13 @@
     mNextTransaction = t;
 }
 
+bool BLASTBufferQueue::rejectBuffer(const BufferItem& item) const {
+    if (item.mScalingMode != NATIVE_WINDOW_SCALING_MODE_FREEZE) {
+        // Only reject buffers if scaling mode is freeze.
+        return false;
+    }
+
+    // reject buffers if the buffer size doesn't match.
+    return item.mGraphicBuffer->getWidth() != mWidth || item.mGraphicBuffer->getHeight() != mHeight;
+}
 } // namespace android
diff --git a/libs/gui/LayerState.cpp b/libs/gui/LayerState.cpp
index 4a57b1b..bde73ba 100644
--- a/libs/gui/LayerState.cpp
+++ b/libs/gui/LayerState.cpp
@@ -18,16 +18,55 @@
 
 #include <inttypes.h>
 
-#include <utils/Errors.h>
 #include <binder/Parcel.h>
-#include <gui/ISurfaceComposerClient.h>
 #include <gui/IGraphicBufferProducer.h>
+#include <gui/ISurfaceComposerClient.h>
 #include <gui/LayerState.h>
+#include <utils/Errors.h>
 
 #include <cmath>
 
 namespace android {
 
+layer_state_t::layer_state_t()
+      : what(0),
+        x(0),
+        y(0),
+        z(0),
+        w(0),
+        h(0),
+        layerStack(0),
+        alpha(0),
+        flags(0),
+        mask(0),
+        reserved(0),
+        crop_legacy(Rect::INVALID_RECT),
+        cornerRadius(0.0f),
+        backgroundBlurRadius(0),
+        barrierFrameNumber(0),
+        overrideScalingMode(-1),
+        transform(0),
+        transformToDisplayInverse(false),
+        crop(Rect::INVALID_RECT),
+        orientedDisplaySpaceRect(Rect::INVALID_RECT),
+        dataspace(ui::Dataspace::UNKNOWN),
+        surfaceDamageRegion(),
+        api(-1),
+        colorTransform(mat4()),
+        bgColorAlpha(0),
+        bgColorDataspace(ui::Dataspace::UNKNOWN),
+        colorSpaceAgnostic(false),
+        shadowRadius(0.0f),
+        frameRateSelectionPriority(-1),
+        frameRate(0.0f),
+        frameRateCompatibility(ANATIVEWINDOW_FRAME_RATE_COMPATIBILITY_DEFAULT),
+        fixedTransformHint(ui::Transform::ROT_INVALID),
+        frameNumber(0) {
+    matrix.dsdx = matrix.dtdy = 1.0f;
+    matrix.dsdy = matrix.dtdx = 0.0f;
+    hdrMetadata.validTypes = 0;
+}
+
 status_t layer_state_t::write(Parcel& output) const
 {
     SAFE_PARCEL(output.writeStrongBinder, surface);
@@ -44,13 +83,12 @@
     SAFE_PARCEL(output.writeUint32, mask);
     SAFE_PARCEL(matrix.write, output);
     SAFE_PARCEL(output.write, crop_legacy);
-    SAFE_PARCEL(output.writeStrongBinder, barrierHandle_legacy);
-    SAFE_PARCEL(output.writeStrongBinder, reparentHandle);
+    SAFE_PARCEL(SurfaceControl::writeNullableToParcel, output, barrierSurfaceControl_legacy);
+    SAFE_PARCEL(SurfaceControl::writeNullableToParcel, output, reparentSurfaceControl);
     SAFE_PARCEL(output.writeUint64, barrierFrameNumber);
     SAFE_PARCEL(output.writeInt32, overrideScalingMode);
-    SAFE_PARCEL(output.writeStrongBinder, IInterface::asBinder(barrierGbp_legacy));
-    SAFE_PARCEL(output.writeStrongBinder, relativeLayerHandle);
-    SAFE_PARCEL(output.writeStrongBinder, parentHandleForChild);
+    SAFE_PARCEL(SurfaceControl::writeNullableToParcel, output, relativeLayerSurfaceControl);
+    SAFE_PARCEL(SurfaceControl::writeNullableToParcel, output, parentSurfaceControlForChild);
     SAFE_PARCEL(output.writeFloat, color.r);
     SAFE_PARCEL(output.writeFloat, color.g);
     SAFE_PARCEL(output.writeFloat, color.b);
@@ -135,18 +173,15 @@
 
     SAFE_PARCEL(matrix.read, input);
     SAFE_PARCEL(input.read, crop_legacy);
-    SAFE_PARCEL(input.readNullableStrongBinder, &barrierHandle_legacy);
-    SAFE_PARCEL(input.readNullableStrongBinder, &reparentHandle);
+    SAFE_PARCEL(SurfaceControl::readNullableFromParcel, input, &barrierSurfaceControl_legacy);
+    SAFE_PARCEL(SurfaceControl::readNullableFromParcel, input, &reparentSurfaceControl);
     SAFE_PARCEL(input.readUint64, &barrierFrameNumber);
     SAFE_PARCEL(input.readInt32, &overrideScalingMode);
 
-    sp<IBinder> tmpBinder;
-    SAFE_PARCEL(input.readNullableStrongBinder, &tmpBinder);
-    barrierGbp_legacy = interface_cast<IGraphicBufferProducer>(tmpBinder);
+    SAFE_PARCEL(SurfaceControl::readNullableFromParcel, input, &relativeLayerSurfaceControl);
+    SAFE_PARCEL(SurfaceControl::readNullableFromParcel, input, &parentSurfaceControlForChild);
 
     float tmpFloat = 0;
-    SAFE_PARCEL(input.readNullableStrongBinder, &relativeLayerHandle);
-    SAFE_PARCEL(input.readNullableStrongBinder, &parentHandleForChild);
     SAFE_PARCEL(input.readFloat, &tmpFloat);
     color.r = tmpFloat;
     SAFE_PARCEL(input.readFloat, &tmpFloat);
@@ -190,6 +225,7 @@
     SAFE_PARCEL(input.read, &colorTransform, 16 * sizeof(float));
     SAFE_PARCEL(input.readFloat, &cornerRadius);
     SAFE_PARCEL(input.readUint32, &backgroundBlurRadius);
+    sp<IBinder> tmpBinder;
     SAFE_PARCEL(input.readNullableStrongBinder, &tmpBinder);
     cachedBuffer.token = tmpBinder;
     SAFE_PARCEL(input.readUint64, &cachedBuffer.id);
@@ -342,8 +378,7 @@
     }
     if (other.what & eDeferTransaction_legacy) {
         what |= eDeferTransaction_legacy;
-        barrierHandle_legacy = other.barrierHandle_legacy;
-        barrierGbp_legacy = other.barrierGbp_legacy;
+        barrierSurfaceControl_legacy = other.barrierSurfaceControl_legacy;
         barrierFrameNumber = other.barrierFrameNumber;
     }
     if (other.what & eOverrideScalingModeChanged) {
@@ -352,7 +387,7 @@
     }
     if (other.what & eReparentChildren) {
         what |= eReparentChildren;
-        reparentHandle = other.reparentHandle;
+        reparentSurfaceControl = other.reparentSurfaceControl;
     }
     if (other.what & eDetachChildren) {
         what |= eDetachChildren;
@@ -361,11 +396,11 @@
         what |= eRelativeLayerChanged;
         what &= ~eLayerChanged;
         z = other.z;
-        relativeLayerHandle = other.relativeLayerHandle;
+        relativeLayerSurfaceControl = other.relativeLayerSurfaceControl;
     }
     if (other.what & eReparent) {
         what |= eReparent;
-        parentHandleForChild = other.parentHandleForChild;
+        parentSurfaceControlForChild = other.parentSurfaceControlForChild;
     }
     if (other.what & eDestroySurface) {
         what |= eDestroySurface;
diff --git a/libs/gui/SurfaceComposerClient.cpp b/libs/gui/SurfaceComposerClient.cpp
index 2f6a34b..0068ccf 100644
--- a/libs/gui/SurfaceComposerClient.cpp
+++ b/libs/gui/SurfaceComposerClient.cpp
@@ -875,8 +875,8 @@
     return *this;
 }
 
-SurfaceComposerClient::Transaction& SurfaceComposerClient::Transaction::setRelativeLayer(const sp<SurfaceControl>& sc, const sp<IBinder>& relativeTo,
-        int32_t z) {
+SurfaceComposerClient::Transaction& SurfaceComposerClient::Transaction::setRelativeLayer(
+        const sp<SurfaceControl>& sc, const sp<SurfaceControl>& relativeTo, int32_t z) {
     layer_state_t* s = getLayerState(sc);
     if (!s) {
         mStatus = BAD_INDEX;
@@ -884,7 +884,7 @@
     }
     s->what |= layer_state_t::eRelativeLayerChanged;
     s->what &= ~layer_state_t::eLayerChanged;
-    s->relativeLayerHandle = relativeTo;
+    s->relativeLayerSurfaceControl = relativeTo;
     s->z = z;
 
     registerSurfaceControlForCallback(sc);
@@ -1028,33 +1028,16 @@
 }
 
 SurfaceComposerClient::Transaction&
-SurfaceComposerClient::Transaction::deferTransactionUntil_legacy(const sp<SurfaceControl>& sc,
-                                                                 const sp<IBinder>& handle,
-                                                                 uint64_t frameNumber) {
+SurfaceComposerClient::Transaction::deferTransactionUntil_legacy(
+        const sp<SurfaceControl>& sc, const sp<SurfaceControl>& barrierSurfaceControl,
+        uint64_t frameNumber) {
     layer_state_t* s = getLayerState(sc);
     if (!s) {
         mStatus = BAD_INDEX;
         return *this;
     }
     s->what |= layer_state_t::eDeferTransaction_legacy;
-    s->barrierHandle_legacy = handle;
-    s->barrierFrameNumber = frameNumber;
-
-    registerSurfaceControlForCallback(sc);
-    return *this;
-}
-
-SurfaceComposerClient::Transaction&
-SurfaceComposerClient::Transaction::deferTransactionUntil_legacy(const sp<SurfaceControl>& sc,
-                                                                 const sp<Surface>& barrierSurface,
-                                                                 uint64_t frameNumber) {
-    layer_state_t* s = getLayerState(sc);
-    if (!s) {
-        mStatus = BAD_INDEX;
-        return *this;
-    }
-    s->what |= layer_state_t::eDeferTransaction_legacy;
-    s->barrierGbp_legacy = barrierSurface->getIGraphicBufferProducer();
+    s->barrierSurfaceControl_legacy = barrierSurfaceControl;
     s->barrierFrameNumber = frameNumber;
 
     registerSurfaceControlForCallback(sc);
@@ -1062,30 +1045,28 @@
 }
 
 SurfaceComposerClient::Transaction& SurfaceComposerClient::Transaction::reparentChildren(
-        const sp<SurfaceControl>& sc,
-        const sp<IBinder>& newParentHandle) {
+        const sp<SurfaceControl>& sc, const sp<SurfaceControl>& newParent) {
     layer_state_t* s = getLayerState(sc);
     if (!s) {
         mStatus = BAD_INDEX;
         return *this;
     }
     s->what |= layer_state_t::eReparentChildren;
-    s->reparentHandle = newParentHandle;
+    s->reparentSurfaceControl = newParent;
 
     registerSurfaceControlForCallback(sc);
     return *this;
 }
 
 SurfaceComposerClient::Transaction& SurfaceComposerClient::Transaction::reparent(
-        const sp<SurfaceControl>& sc,
-        const sp<IBinder>& newParentHandle) {
+        const sp<SurfaceControl>& sc, const sp<SurfaceControl>& newParent) {
     layer_state_t* s = getLayerState(sc);
     if (!s) {
         mStatus = BAD_INDEX;
         return *this;
     }
     s->what |= layer_state_t::eReparent;
-    s->parentHandleForChild = newParentHandle;
+    s->parentSurfaceControlForChild = newParent;
 
     registerSurfaceControlForCallback(sc);
     return *this;
diff --git a/libs/gui/SurfaceControl.cpp b/libs/gui/SurfaceControl.cpp
index e37ff89..e842382 100644
--- a/libs/gui/SurfaceControl.cpp
+++ b/libs/gui/SurfaceControl.cpp
@@ -24,6 +24,7 @@
 #include <android/native_window.h>
 
 #include <utils/Errors.h>
+#include <utils/KeyedVector.h>
 #include <utils/Log.h>
 #include <utils/threads.h>
 
diff --git a/libs/gui/include/gui/BLASTBufferQueue.h b/libs/gui/include/gui/BLASTBufferQueue.h
index 35c656a..5b1a018 100644
--- a/libs/gui/include/gui/BLASTBufferQueue.h
+++ b/libs/gui/include/gui/BLASTBufferQueue.h
@@ -94,6 +94,8 @@
 
     void processNextBufferLocked(bool useNextTransaction) REQUIRES(mMutex);
     Rect computeCrop(const BufferItem& item);
+    // Return true if we need to reject the buffer based on the scaling mode and the buffer size.
+    bool rejectBuffer(const BufferItem& item) const;
 
     std::string mName;
     sp<SurfaceControl> mSurfaceControl;
@@ -107,6 +109,7 @@
 
     int32_t mNumFrameAvailable GUARDED_BY(mMutex);
     int32_t mNumAcquired GUARDED_BY(mMutex);
+    bool mInitialCallbackReceived GUARDED_BY(mMutex) = false;
     struct PendingReleaseItem {
         BufferItem item;
         sp<Fence> releaseFence;
diff --git a/libs/gui/include/gui/LayerState.h b/libs/gui/include/gui/LayerState.h
index 65fd9ab..fed0ef3 100644
--- a/libs/gui/include/gui/LayerState.h
+++ b/libs/gui/include/gui/LayerState.h
@@ -49,6 +49,7 @@
 
 #include <gui/ISurfaceComposer.h>
 #include <gui/LayerMetadata.h>
+#include <gui/SurfaceControl.h>
 #include <math/vec3.h>
 #include <ui/GraphicTypes.h>
 #include <ui/Rect.h>
@@ -128,44 +129,7 @@
         eFrameNumberChanged = 0x400'00000000,
     };
 
-    layer_state_t()
-          : what(0),
-            x(0),
-            y(0),
-            z(0),
-            w(0),
-            h(0),
-            layerStack(0),
-            alpha(0),
-            flags(0),
-            mask(0),
-            reserved(0),
-            crop_legacy(Rect::INVALID_RECT),
-            cornerRadius(0.0f),
-            backgroundBlurRadius(0),
-            barrierFrameNumber(0),
-            overrideScalingMode(-1),
-            transform(0),
-            transformToDisplayInverse(false),
-            crop(Rect::INVALID_RECT),
-            orientedDisplaySpaceRect(Rect::INVALID_RECT),
-            dataspace(ui::Dataspace::UNKNOWN),
-            surfaceDamageRegion(),
-            api(-1),
-            colorTransform(mat4()),
-            bgColorAlpha(0),
-            bgColorDataspace(ui::Dataspace::UNKNOWN),
-            colorSpaceAgnostic(false),
-            shadowRadius(0.0f),
-            frameRateSelectionPriority(-1),
-            frameRate(0.0f),
-            frameRateCompatibility(ANATIVEWINDOW_FRAME_RATE_COMPATIBILITY_DEFAULT),
-            fixedTransformHint(ui::Transform::ROT_INVALID),
-            frameNumber(0) {
-        matrix.dsdx = matrix.dtdy = 1.0f;
-        matrix.dsdy = matrix.dtdx = 0.0f;
-        hdrMetadata.validTypes = 0;
-    }
+    layer_state_t();
 
     void merge(const layer_state_t& other);
     status_t write(Parcel& output) const;
@@ -196,16 +160,14 @@
     Rect crop_legacy;
     float cornerRadius;
     uint32_t backgroundBlurRadius;
-    sp<IBinder> barrierHandle_legacy;
-    sp<IBinder> reparentHandle;
+    sp<SurfaceControl> barrierSurfaceControl_legacy;
+    sp<SurfaceControl> reparentSurfaceControl;
     uint64_t barrierFrameNumber;
     int32_t overrideScalingMode;
 
-    sp<IGraphicBufferProducer> barrierGbp_legacy;
+    sp<SurfaceControl> relativeLayerSurfaceControl;
 
-    sp<IBinder> relativeLayerHandle;
-
-    sp<IBinder> parentHandleForChild;
+    sp<SurfaceControl> parentSurfaceControlForChild;
 
     half3 color;
 
diff --git a/libs/gui/include/gui/SurfaceComposerClient.h b/libs/gui/include/gui/SurfaceComposerClient.h
index cc82502..277060f 100644
--- a/libs/gui/include/gui/SurfaceComposerClient.h
+++ b/libs/gui/include/gui/SurfaceComposerClient.h
@@ -424,7 +424,7 @@
         // If the relative is removed, the Surface will have no layer and be
         // invisible, until the next time set(Relative)Layer is called.
         Transaction& setRelativeLayer(const sp<SurfaceControl>& sc,
-                const sp<IBinder>& relativeTo, int32_t z);
+                                      const sp<SurfaceControl>& relativeTo, int32_t z);
         Transaction& setFlags(const sp<SurfaceControl>& sc,
                 uint32_t flags, uint32_t mask);
         Transaction& setTransparentRegionHint(const sp<SurfaceControl>& sc,
@@ -444,22 +444,16 @@
         // by handle is removed, then we will apply this transaction regardless of
         // what frame number has been reached.
         Transaction& deferTransactionUntil_legacy(const sp<SurfaceControl>& sc,
-                                                  const sp<IBinder>& handle, uint64_t frameNumber);
-        // A variant of deferTransactionUntil_legacy which identifies the Layer we wait for by
-        // Surface instead of Handle. Useful for clients which may not have the
-        // SurfaceControl for some of their Surfaces. Otherwise behaves identically.
-        Transaction& deferTransactionUntil_legacy(const sp<SurfaceControl>& sc,
-                                                  const sp<Surface>& barrierSurface,
+                                                  const sp<SurfaceControl>& barrierSurfaceControl,
                                                   uint64_t frameNumber);
         // Reparents all children of this layer to the new parent handle.
         Transaction& reparentChildren(const sp<SurfaceControl>& sc,
-                const sp<IBinder>& newParentHandle);
+                                      const sp<SurfaceControl>& newParent);
 
         /// Reparents the current layer to the new parent handle. The new parent must not be null.
         // This can be used instead of reparentChildren if the caller wants to
         // only re-parent a specific child.
-        Transaction& reparent(const sp<SurfaceControl>& sc,
-                const sp<IBinder>& newParentHandle);
+        Transaction& reparent(const sp<SurfaceControl>& sc, const sp<SurfaceControl>& newParent);
 
         Transaction& setColor(const sp<SurfaceControl>& sc, const half3& color);
 
diff --git a/libs/gui/include/gui/SurfaceControl.h b/libs/gui/include/gui/SurfaceControl.h
index c0dfcdb..35bdfc1 100644
--- a/libs/gui/include/gui/SurfaceControl.h
+++ b/libs/gui/include/gui/SurfaceControl.h
@@ -20,7 +20,6 @@
 #include <stdint.h>
 #include <sys/types.h>
 
-#include <utils/KeyedVector.h>
 #include <utils/RefBase.h>
 #include <utils/threads.h>
 
diff --git a/libs/gui/tests/EndToEndNativeInputTest.cpp b/libs/gui/tests/EndToEndNativeInputTest.cpp
index ef4d870..483f171 100644
--- a/libs/gui/tests/EndToEndNativeInputTest.cpp
+++ b/libs/gui/tests/EndToEndNativeInputTest.cpp
@@ -381,7 +381,7 @@
 
     childSurface->doTransaction([&](auto &t, auto &sc) {
         t.setPosition(sc, -5, -5);
-        t.reparent(sc, parentSurface->mSurfaceControl->getHandle());
+        t.reparent(sc, parentSurface->mSurfaceControl);
     });
 
     injectTap(106, 106);
diff --git a/libs/input/InputEventLabels.cpp b/libs/input/InputEventLabels.cpp
index dee240c..c0aa2e2 100644
--- a/libs/input/InputEventLabels.cpp
+++ b/libs/input/InputEventLabels.cpp
@@ -348,6 +348,9 @@
     DEFINE_AXIS(SCROLL), \
     DEFINE_AXIS(RELATIVE_X), \
     DEFINE_AXIS(RELATIVE_Y), \
+    {"RESERVED_29", 29}, \
+    {"RESERVED_30", 30}, \
+    {"RESERVED_31", 31}, \
     DEFINE_AXIS(GENERIC_1), \
     DEFINE_AXIS(GENERIC_2), \
     DEFINE_AXIS(GENERIC_3), \
diff --git a/libs/input/tests/Android.bp b/libs/input/tests/Android.bp
index 7ff5ab6..44147a5 100644
--- a/libs/input/tests/Android.bp
+++ b/libs/input/tests/Android.bp
@@ -2,6 +2,7 @@
 cc_test {
     name: "libinput_tests",
     srcs: [
+        "NamedEnum_test.cpp",
         "Flags_test.cpp",
         "IdGenerator_test.cpp",
         "InputChannel_test.cpp",
diff --git a/libs/input/tests/NamedEnum_test.cpp b/libs/input/tests/NamedEnum_test.cpp
new file mode 100644
index 0000000..4e93f71
--- /dev/null
+++ b/libs/input/tests/NamedEnum_test.cpp
@@ -0,0 +1,101 @@
+/*
+ * Copyright 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <gtest/gtest.h>
+#include <input/NamedEnum.h>
+
+namespace android {
+
+// Test enum class maximum enum value smaller than default maximum of 8.
+enum class TestEnums { ZERO = 0x0, ONE = 0x1, TWO = 0x2, THREE = 0x3, SEVEN = 0x7 };
+// Big enum contains enum values greater than default maximum of 8.
+enum class TestBigEnums { ZERO = 0x0, FIFTEEN = 0xF };
+
+// Declared to specialize the maximum enum since the enum size exceeds 8 by default.
+template <>
+constexpr size_t NamedEnum::max<TestBigEnums> = 16;
+
+namespace test {
+using android::TestBigEnums;
+using android::TestEnums;
+
+TEST(NamedEnum, RuntimeNamedEnum) {
+    TestEnums e = TestEnums::ZERO;
+    ASSERT_EQ(NamedEnum::enum_name(e), "ZERO");
+
+    e = TestEnums::ONE;
+    ASSERT_EQ(NamedEnum::enum_name(e), "ONE");
+
+    e = TestEnums::THREE;
+    ASSERT_EQ(NamedEnum::enum_name(e), "THREE");
+
+    e = TestEnums::SEVEN;
+    ASSERT_EQ(NamedEnum::enum_name(e), "SEVEN");
+}
+
+// Test big enum
+TEST(NamedEnum, RuntimeBigNamedEnum) {
+    TestBigEnums e = TestBigEnums::ZERO;
+    ASSERT_EQ(NamedEnum::enum_name(e), "ZERO");
+
+    e = TestBigEnums::FIFTEEN;
+    ASSERT_EQ(NamedEnum::enum_name(e), "FIFTEEN");
+}
+
+TEST(NamedEnum, RuntimeNamedEnumAsString) {
+    TestEnums e = TestEnums::ZERO;
+    ASSERT_EQ(NamedEnum::string(e), "ZERO");
+
+    e = TestEnums::ONE;
+    ASSERT_EQ(NamedEnum::string(e), "ONE");
+
+    e = TestEnums::THREE;
+    ASSERT_EQ(NamedEnum::string(e), "THREE");
+
+    e = TestEnums::SEVEN;
+    ASSERT_EQ(NamedEnum::string(e), "SEVEN");
+}
+
+TEST(NamedEnum, RuntimeBigNamedEnumAsString) {
+    TestBigEnums e = TestBigEnums::ZERO;
+    ASSERT_EQ(NamedEnum::string(e), "ZERO");
+
+    e = TestBigEnums::FIFTEEN;
+    ASSERT_EQ(NamedEnum::string(e), "FIFTEEN");
+}
+
+TEST(NamedEnum, RuntimeUnknownNamedEnum) {
+    TestEnums e = static_cast<TestEnums>(0x5);
+    ASSERT_EQ(NamedEnum::enum_name(e), std::nullopt);
+    e = static_cast<TestEnums>(0x9);
+    ASSERT_EQ(NamedEnum::enum_name(e), std::nullopt);
+}
+
+TEST(NamedEnum, RuntimeUnknownNamedEnumAsString) {
+    TestEnums e = static_cast<TestEnums>(0x5);
+    ASSERT_EQ(NamedEnum::string(e), "0x00000005");
+    e = static_cast<TestEnums>(0x9);
+    ASSERT_EQ(NamedEnum::string(e), "0x00000009");
+}
+
+TEST(NamedEnum, CompileTimeFlagName) {
+    static_assert(NamedEnum::enum_name<TestEnums::TWO>() == "TWO");
+    static_assert(NamedEnum::enum_name<TestEnums::THREE>() == "THREE");
+}
+
+} // namespace test
+
+} // namespace android
diff --git a/libs/renderengine/include/renderengine/DisplaySettings.h b/libs/renderengine/include/renderengine/DisplaySettings.h
index ca16d2c..a637796 100644
--- a/libs/renderengine/include/renderengine/DisplaySettings.h
+++ b/libs/renderengine/include/renderengine/DisplaySettings.h
@@ -47,8 +47,8 @@
     // DataSpace::UNKNOWN otherwise.
     ui::Dataspace outputDataspace = ui::Dataspace::UNKNOWN;
 
-    // Additional color transform to apply in linear space after transforming
-    // to the output dataspace.
+    // Additional color transform to apply after transforming to the output
+    // dataspace, in non-linear space.
     mat4 colorTransform = mat4();
 
     // Region that will be cleared to (0, 0, 0, 1) prior to rendering.
diff --git a/libs/renderengine/skia/SkiaGLRenderEngine.cpp b/libs/renderengine/skia/SkiaGLRenderEngine.cpp
index afedd48..69ad189 100644
--- a/libs/renderengine/skia/SkiaGLRenderEngine.cpp
+++ b/libs/renderengine/skia/SkiaGLRenderEngine.cpp
@@ -15,17 +15,18 @@
  */
 
 //#define LOG_NDEBUG 0
+#include <cstdint>
 #undef LOG_TAG
 #define LOG_TAG "RenderEngine"
 #define ATRACE_TAG ATRACE_TAG_GRAPHICS
 
-#include "SkiaGLRenderEngine.h"
-
 #include <EGL/egl.h>
 #include <EGL/eglext.h>
 #include <GLES2/gl2.h>
 #include <GrContextOptions.h>
 #include <SkCanvas.h>
+#include <SkColorFilter.h>
+#include <SkColorMatrix.h>
 #include <SkColorSpace.h>
 #include <SkImage.h>
 #include <SkImageFilters.h>
@@ -39,6 +40,7 @@
 #include <cmath>
 
 #include "../gl/GLExtensions.h"
+#include "SkiaGLRenderEngine.h"
 #include "filters/BlurFilter.h"
 
 extern "C" EGLAPI const char* eglQueryStringImplementationANDROID(EGLDisplay dpy, EGLint name);
@@ -381,6 +383,26 @@
     return !!(desc.usage & usage);
 }
 
+static float toDegrees(uint32_t transform) {
+    switch (transform) {
+        case ui::Transform::ROT_90:
+            return 90.0;
+        case ui::Transform::ROT_180:
+            return 180.0;
+        case ui::Transform::ROT_270:
+            return 270.0;
+        default:
+            return 0.0;
+    }
+}
+
+static SkColorMatrix toSkColorMatrix(const mat4& matrix) {
+    return SkColorMatrix(matrix[0][0], matrix[1][0], matrix[2][0], matrix[3][0], 0, matrix[0][1],
+                         matrix[1][1], matrix[2][1], matrix[3][1], 0, matrix[0][2], matrix[1][2],
+                         matrix[2][2], matrix[3][2], 0, matrix[0][3], matrix[1][3], matrix[2][3],
+                         matrix[3][3], 0);
+}
+
 void SkiaGLRenderEngine::unbindExternalTextureBuffer(uint64_t bufferId) {
     std::lock_guard<std::mutex> lock(mRenderingMutex);
     mImageCache.erase(bufferId);
@@ -441,20 +463,39 @@
         ALOGE("Failed to make surface");
         return BAD_VALUE;
     }
+
     auto canvas = surface->getCanvas();
+    // Clear the entire canvas with a transparent black to prevent ghost images.
+    canvas->clear(SK_ColorTRANSPARENT);
     canvas->save();
 
     // Before doing any drawing, let's make sure that we'll start at the origin of the display.
     // Some displays don't start at 0,0 for example when we're mirroring the screen. Also, virtual
     // displays might have different scaling when compared to the physical screen.
+
+    canvas->clipRect(getSkRect(display.physicalDisplay));
     canvas->translate(display.physicalDisplay.left, display.physicalDisplay.top);
+
+    const auto clipWidth = display.clip.width();
+    const auto clipHeight = display.clip.height();
+    auto rotatedClipWidth = clipWidth;
+    auto rotatedClipHeight = clipHeight;
+    // Scale is contingent on the rotation result.
+    if (display.orientation & ui::Transform::ROT_90) {
+        std::swap(rotatedClipWidth, rotatedClipHeight);
+    }
     const auto scaleX = static_cast<SkScalar>(display.physicalDisplay.width()) /
-            static_cast<SkScalar>(display.clip.width());
+            static_cast<SkScalar>(rotatedClipWidth);
     const auto scaleY = static_cast<SkScalar>(display.physicalDisplay.height()) /
-            static_cast<SkScalar>(display.clip.height());
+            static_cast<SkScalar>(rotatedClipHeight);
     canvas->scale(scaleX, scaleY);
-    canvas->clipRect(getSkRect(display.clip));
-    canvas->drawColor(0, SkBlendMode::kSrc);
+
+    // Canvas rotation is done by centering the clip window at the origin, rotating, translating
+    // back so that the top left corner of the clip is at (0, 0).
+    canvas->translate(rotatedClipWidth / 2, rotatedClipHeight / 2);
+    canvas->rotate(toDegrees(display.orientation));
+    canvas->translate(-clipWidth / 2, -clipHeight / 2);
+    canvas->translate(-display.clip.left, -display.clip.top);
     for (const auto& layer : layers) {
         SkPaint paint;
         const auto& bounds = layer->geometry.boundaries;
@@ -468,6 +509,8 @@
         if (layer->source.buffer.buffer) {
             ATRACE_NAME("DrawImage");
             const auto& item = layer->source.buffer;
+            const auto bufferWidth = item.buffer->getBounds().width();
+            const auto bufferHeight = item.buffer->getBounds().height();
             sk_sp<SkImage> image;
             auto iter = mImageCache.find(item.buffer->getId());
             if (iter != mImageCache.end()) {
@@ -492,6 +535,38 @@
             } else {
                 matrix.setIdentity();
             }
+
+            auto texMatrix = getSkM44(item.textureTransform).asM33();
+            // textureTansform was intended to be passed directly into a shader, so when
+            // building the total matrix with the textureTransform we need to first
+            // normalize it, then apply the textureTransform, then scale back up.
+            matrix.postScale(1.0f / bufferWidth, 1.0f / bufferHeight);
+
+            auto rotatedBufferWidth = bufferWidth;
+            auto rotatedBufferHeight = bufferHeight;
+
+            // Swap the buffer width and height if we're rotating, so that we
+            // scale back up by the correct factors post-rotation.
+            if (texMatrix.getSkewX() <= -0.5f || texMatrix.getSkewX() >= 0.5f) {
+                std::swap(rotatedBufferWidth, rotatedBufferHeight);
+                // TODO: clean this up.
+                // GLESRenderEngine specifies its texture coordinates in
+                // CW orientation under OpenGL conventions, when they probably should have
+                // been CCW instead. The net result is that orientation
+                // transforms are applied in the reverse
+                // direction to render the correct result, because SurfaceFlinger uses the inverse
+                // of the display transform to correct for that. But this means that
+                // the tex transform passed by SkiaGLRenderEngine will rotate
+                // individual layers in the reverse orientation. Hack around it
+                // by injected a 180 degree rotation, but ultimately this is
+                // a bug in how SurfaceFlinger invokes the RenderEngine
+                // interface, so the proper fix should live there, and GLESRenderEngine
+                // should be fixed accordingly.
+                matrix.postRotate(180, 0.5, 0.5);
+            }
+
+            matrix.postConcat(texMatrix);
+            matrix.postScale(rotatedBufferWidth, rotatedBufferHeight);
             paint.setShader(image->makeShader(matrix));
         } else {
             ATRACE_NAME("DrawColor");
@@ -499,6 +574,8 @@
             paint.setColor(SkColor4f{.fR = color.r, .fG = color.g, .fB = color.b, layer->alpha});
         }
 
+        paint.setColorFilter(SkColorFilters::Matrix(toSkColorMatrix(display.colorTransform)));
+
         // Layers have a local transform matrix that should be applied to them.
         canvas->save();
         canvas->concat(getSkM44(layer->geometry.positionTransform));
diff --git a/libs/ui/include/ui/DisplayId.h b/libs/ui/include/ui/DisplayId.h
index 9eb5483..f196ab9 100644
--- a/libs/ui/include/ui/DisplayId.h
+++ b/libs/ui/include/ui/DisplayId.h
@@ -17,13 +17,20 @@
 #pragma once
 
 #include <cstdint>
-#include <functional>
+#include <optional>
 #include <string>
 
 namespace android {
 
 // ID of a physical or a virtual display. This class acts as a type safe wrapper around uint64_t.
+// The encoding of the ID is type-specific for bits 0 to 61.
 struct DisplayId {
+    // Flag indicating that the display is virtual.
+    static constexpr uint64_t FLAG_VIRTUAL = 1ULL << 63;
+
+    // Flag indicating that the ID is stable across reboots.
+    static constexpr uint64_t FLAG_STABLE = 1ULL << 62;
+
     // TODO(b/162612135) Remove default constructor
     DisplayId() = default;
     constexpr DisplayId(const DisplayId&) = default;
@@ -51,8 +58,12 @@
 
 // DisplayId of a physical display, such as the internal display or externally connected display.
 struct PhysicalDisplayId : DisplayId {
-    // Flag indicating that the ID is stable across reboots.
-    static constexpr uint64_t FLAG_STABLE = 1ULL << 62;
+    static constexpr std::optional<PhysicalDisplayId> tryCast(DisplayId id) {
+        if (id.value & FLAG_VIRTUAL) {
+            return std::nullopt;
+        }
+        return {PhysicalDisplayId(id)};
+    }
 
     // Returns a stable ID based on EDID information.
     static constexpr PhysicalDisplayId fromEdid(uint8_t port, uint16_t manufacturerId,
@@ -69,8 +80,8 @@
 
     // TODO(b/162612135) Remove default constructor
     PhysicalDisplayId() = default;
+    // TODO(b/162612135) Remove constructor
     explicit constexpr PhysicalDisplayId(uint64_t id) : DisplayId(id) {}
-    explicit constexpr PhysicalDisplayId(DisplayId other) : DisplayId(other.value) {}
 
     constexpr uint16_t getManufacturerId() const { return static_cast<uint16_t>(value >> 40); }
 
@@ -81,10 +92,82 @@
                                 uint32_t modelHash)
           : DisplayId(flags | (static_cast<uint64_t>(manufacturerId) << 40) |
                       (static_cast<uint64_t>(modelHash) << 8) | port) {}
+
+    explicit constexpr PhysicalDisplayId(DisplayId other) : DisplayId(other) {}
 };
 
 static_assert(sizeof(PhysicalDisplayId) == sizeof(uint64_t));
 
+struct VirtualDisplayId : DisplayId {
+    using BaseId = uint32_t;
+    // Flag indicating that this virtual display is backed by the GPU.
+    static constexpr uint64_t FLAG_GPU = 1ULL << 61;
+
+    static constexpr std::optional<VirtualDisplayId> tryCast(DisplayId id) {
+        if (id.value & FLAG_VIRTUAL) {
+            return {VirtualDisplayId(id)};
+        }
+        return std::nullopt;
+    }
+
+protected:
+    constexpr VirtualDisplayId(uint64_t flags, BaseId baseId)
+          : DisplayId(DisplayId::FLAG_VIRTUAL | flags | baseId) {}
+
+    explicit constexpr VirtualDisplayId(DisplayId other) : DisplayId(other) {}
+};
+
+struct HalVirtualDisplayId : VirtualDisplayId {
+    explicit constexpr HalVirtualDisplayId(BaseId baseId) : VirtualDisplayId(0, baseId) {}
+
+    static constexpr std::optional<HalVirtualDisplayId> tryCast(DisplayId id) {
+        if ((id.value & FLAG_VIRTUAL) && !(id.value & VirtualDisplayId::FLAG_GPU)) {
+            return {HalVirtualDisplayId(id)};
+        }
+        return std::nullopt;
+    }
+
+private:
+    explicit constexpr HalVirtualDisplayId(DisplayId other) : VirtualDisplayId(other) {}
+};
+
+struct GpuVirtualDisplayId : VirtualDisplayId {
+    explicit constexpr GpuVirtualDisplayId(BaseId baseId)
+          : VirtualDisplayId(VirtualDisplayId::FLAG_GPU, baseId) {}
+
+    static constexpr std::optional<GpuVirtualDisplayId> tryCast(DisplayId id) {
+        if ((id.value & FLAG_VIRTUAL) && (id.value & VirtualDisplayId::FLAG_GPU)) {
+            return {GpuVirtualDisplayId(id)};
+        }
+        return std::nullopt;
+    }
+
+private:
+    explicit constexpr GpuVirtualDisplayId(DisplayId other) : VirtualDisplayId(other) {}
+};
+
+// HalDisplayId is the ID of a display which is managed by HWC.
+// PhysicalDisplayId and HalVirtualDisplayId are implicitly convertible to HalDisplayId.
+struct HalDisplayId : DisplayId {
+    constexpr HalDisplayId(HalVirtualDisplayId other) : DisplayId(other) {}
+    constexpr HalDisplayId(PhysicalDisplayId other) : DisplayId(other) {}
+
+    static constexpr std::optional<HalDisplayId> tryCast(DisplayId id) {
+        if (GpuVirtualDisplayId::tryCast(id)) {
+            return std::nullopt;
+        }
+        return {HalDisplayId(id)};
+    }
+
+private:
+    explicit constexpr HalDisplayId(DisplayId other) : DisplayId(other) {}
+};
+
+static_assert(sizeof(VirtualDisplayId) == sizeof(uint64_t));
+static_assert(sizeof(HalVirtualDisplayId) == sizeof(uint64_t));
+static_assert(sizeof(GpuVirtualDisplayId) == sizeof(uint64_t));
+static_assert(sizeof(HalDisplayId) == sizeof(uint64_t));
+
 } // namespace android
 
 namespace std {
@@ -99,4 +182,13 @@
 template <>
 struct hash<android::PhysicalDisplayId> : hash<android::DisplayId> {};
 
+template <>
+struct hash<android::HalVirtualDisplayId> : hash<android::DisplayId> {};
+
+template <>
+struct hash<android::GpuVirtualDisplayId> : hash<android::DisplayId> {};
+
+template <>
+struct hash<android::HalDisplayId> : hash<android::DisplayId> {};
+
 } // namespace std
diff --git a/libs/ui/tests/Android.bp b/libs/ui/tests/Android.bp
index 032dd4c..d005ce8 100644
--- a/libs/ui/tests/Android.bp
+++ b/libs/ui/tests/Android.bp
@@ -29,6 +29,13 @@
 }
 
 cc_test {
+    name: "DisplayId_test",
+    shared_libs: ["libui"],
+    srcs: ["DisplayId_test.cpp"],
+    cflags: ["-Wall", "-Werror"],
+}
+
+cc_test {
     name: "FlattenableHelpers_test",
     shared_libs: ["libui"],
     srcs: ["FlattenableHelpers_test.cpp"],
diff --git a/libs/ui/tests/DisplayId_test.cpp b/libs/ui/tests/DisplayId_test.cpp
new file mode 100644
index 0000000..1d908b8
--- /dev/null
+++ b/libs/ui/tests/DisplayId_test.cpp
@@ -0,0 +1,66 @@
+/*
+ * Copyright 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <ui/DisplayId.h>
+
+#include <gtest/gtest.h>
+
+namespace android::ui {
+
+TEST(DisplayIdTest, createPhysicalIdFromEdid) {
+    constexpr uint8_t port = 1;
+    constexpr uint16_t manufacturerId = 13;
+    constexpr uint32_t modelHash = 42;
+    PhysicalDisplayId id = PhysicalDisplayId::fromEdid(port, manufacturerId, modelHash);
+    EXPECT_EQ(port, id.getPort());
+    EXPECT_EQ(manufacturerId, id.getManufacturerId());
+    EXPECT_FALSE(VirtualDisplayId::tryCast(id));
+    EXPECT_FALSE(HalVirtualDisplayId::tryCast(id));
+    EXPECT_FALSE(GpuVirtualDisplayId::tryCast(id));
+    EXPECT_TRUE(PhysicalDisplayId::tryCast(id));
+    EXPECT_TRUE(HalDisplayId::tryCast(id));
+}
+
+TEST(DisplayIdTest, createPhysicalIdFromPort) {
+    constexpr uint8_t port = 3;
+    PhysicalDisplayId id = PhysicalDisplayId::fromPort(port);
+    EXPECT_EQ(port, id.getPort());
+    EXPECT_FALSE(VirtualDisplayId::tryCast(id));
+    EXPECT_FALSE(HalVirtualDisplayId::tryCast(id));
+    EXPECT_FALSE(GpuVirtualDisplayId::tryCast(id));
+    EXPECT_TRUE(PhysicalDisplayId::tryCast(id));
+    EXPECT_TRUE(HalDisplayId::tryCast(id));
+}
+
+TEST(DisplayIdTest, createGpuVirtualId) {
+    GpuVirtualDisplayId id(42);
+    EXPECT_TRUE(VirtualDisplayId::tryCast(id));
+    EXPECT_TRUE(GpuVirtualDisplayId::tryCast(id));
+    EXPECT_FALSE(HalVirtualDisplayId::tryCast(id));
+    EXPECT_FALSE(PhysicalDisplayId::tryCast(id));
+    EXPECT_FALSE(HalDisplayId::tryCast(id));
+}
+
+TEST(DisplayIdTest, createHalVirtualId) {
+    HalVirtualDisplayId id(42);
+    EXPECT_TRUE(VirtualDisplayId::tryCast(id));
+    EXPECT_TRUE(HalVirtualDisplayId::tryCast(id));
+    EXPECT_FALSE(GpuVirtualDisplayId::tryCast(id));
+    EXPECT_FALSE(PhysicalDisplayId::tryCast(id));
+    EXPECT_TRUE(HalDisplayId::tryCast(id));
+}
+
+} // namespace android::ui
diff --git a/services/inputflinger/dispatcher/InputDispatcher.cpp b/services/inputflinger/dispatcher/InputDispatcher.cpp
index 3ccb0c9..efe2bb1 100644
--- a/services/inputflinger/dispatcher/InputDispatcher.cpp
+++ b/services/inputflinger/dispatcher/InputDispatcher.cpp
@@ -2109,9 +2109,9 @@
     auto otherInfo = otherHandle->getInfo();
     if (!otherInfo->visible) {
         return false;
-    } else if (info->ownerPid == otherInfo->ownerPid) {
-        // If ownerPid is the same we don't generate occlusion events as there
-        // is no in-process security boundary.
+    } else if (info->ownerUid == otherInfo->ownerUid) {
+        // If ownerUid is the same we don't generate occlusion events as there
+        // is no security boundary within an uid.
         return false;
     } else if (otherInfo->trustedOverlay) {
         return false;
diff --git a/services/inputflinger/reader/mapper/TouchInputMapper.cpp b/services/inputflinger/reader/mapper/TouchInputMapper.cpp
index e957826..ea84835 100644
--- a/services/inputflinger/reader/mapper/TouchInputMapper.cpp
+++ b/services/inputflinger/reader/mapper/TouchInputMapper.cpp
@@ -18,6 +18,7 @@
 #include "../Macros.h"
 // clang-format on
 
+#include <input/NamedEnum.h>
 #include "TouchInputMapper.h"
 
 #include "CursorButtonAccumulator.h"
@@ -257,7 +258,8 @@
 }
 
 void TouchInputMapper::dump(std::string& dump) {
-    dump += StringPrintf(INDENT2 "Touch Input Mapper (mode - %s):\n", modeToString(mDeviceMode));
+    dump += StringPrintf(INDENT2 "Touch Input Mapper (mode - %s):\n",
+                         NamedEnum::string(mDeviceMode).c_str());
     dumpParameters(dump);
     dumpVirtualKeys(dump);
     dumpRawPointerAxes(dump);
@@ -345,22 +347,6 @@
     }
 }
 
-const char* TouchInputMapper::modeToString(DeviceMode deviceMode) {
-    switch (deviceMode) {
-        case DeviceMode::DISABLED:
-            return "disabled";
-        case DeviceMode::DIRECT:
-            return "direct";
-        case DeviceMode::UNSCALED:
-            return "unscaled";
-        case DeviceMode::NAVIGATION:
-            return "navigation";
-        case DeviceMode::POINTER:
-            return "pointer";
-    }
-    return "unknown";
-}
-
 void TouchInputMapper::configure(nsecs_t when, const InputReaderConfiguration* config,
                                  uint32_t changes) {
     InputMapper::configure(when, config, changes);
@@ -512,33 +498,9 @@
 void TouchInputMapper::dumpParameters(std::string& dump) {
     dump += INDENT3 "Parameters:\n";
 
-    switch (mParameters.gestureMode) {
-        case Parameters::GestureMode::SINGLE_TOUCH:
-            dump += INDENT4 "GestureMode: single-touch\n";
-            break;
-        case Parameters::GestureMode::MULTI_TOUCH:
-            dump += INDENT4 "GestureMode: multi-touch\n";
-            break;
-        default:
-            assert(false);
-    }
+    dump += INDENT4 "GestureMode: " + NamedEnum::string(mParameters.gestureMode) + "\n";
 
-    switch (mParameters.deviceType) {
-        case Parameters::DeviceType::TOUCH_SCREEN:
-            dump += INDENT4 "DeviceType: touchScreen\n";
-            break;
-        case Parameters::DeviceType::TOUCH_PAD:
-            dump += INDENT4 "DeviceType: touchPad\n";
-            break;
-        case Parameters::DeviceType::TOUCH_NAVIGATION:
-            dump += INDENT4 "DeviceType: touchNavigation\n";
-            break;
-        case Parameters::DeviceType::POINTER:
-            dump += INDENT4 "DeviceType: pointer\n";
-            break;
-        default:
-            ALOG_ASSERT(false);
-    }
+    dump += INDENT4 "DeviceType: " + NamedEnum::string(mParameters.deviceType) + "\n";
 
     dump += StringPrintf(INDENT4 "AssociatedDisplay: hasAssociatedDisplay=%s, isExternal=%s, "
                                  "displayId='%s'\n",
diff --git a/services/sensorservice/SensorEventConnection.cpp b/services/sensorservice/SensorEventConnection.cpp
index d14a301..3cccaf9 100644
--- a/services/sensorservice/SensorEventConnection.cpp
+++ b/services/sensorservice/SensorEventConnection.cpp
@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+#include <log/log.h>
 #include <sys/socket.h>
 #include <utils/threads.h>
 
@@ -53,20 +54,13 @@
 SensorService::SensorEventConnection::~SensorEventConnection() {
     ALOGD_IF(DEBUG_CONNECTIONS, "~SensorEventConnection(%p)", this);
     destroy();
-}
-
-void SensorService::SensorEventConnection::destroy() {
-    Mutex::Autolock _l(mDestroyLock);
-
-    // destroy once only
-    if (mDestroyed) {
-        return;
-    }
-
     mService->cleanupConnection(this);
     if (mEventCache != nullptr) {
         delete[] mEventCache;
     }
+}
+
+void SensorService::SensorEventConnection::destroy() {
     mDestroyed = true;
 }
 
@@ -679,6 +673,11 @@
         int handle, bool enabled, nsecs_t samplingPeriodNs, nsecs_t maxBatchReportLatencyNs,
         int reservedFlags)
 {
+    if (mDestroyed) {
+        android_errorWriteLog(0x534e4554, "168211968");
+        return DEAD_OBJECT;
+    }
+
     status_t err;
     if (enabled) {
         err = mService->enable(this, handle, samplingPeriodNs, maxBatchReportLatencyNs,
@@ -693,10 +692,19 @@
 status_t SensorService::SensorEventConnection::setEventRate(
         int handle, nsecs_t samplingPeriodNs)
 {
+    if (mDestroyed) {
+        android_errorWriteLog(0x534e4554, "168211968");
+        return DEAD_OBJECT;
+    }
+
     return mService->setEventRate(this, handle, samplingPeriodNs, mOpPackageName);
 }
 
 status_t  SensorService::SensorEventConnection::flush() {
+    if (mDestroyed) {
+        return DEAD_OBJECT;
+    }
+
     return  mService->flushSensor(this, mOpPackageName);
 }
 
diff --git a/services/sensorservice/SensorEventConnection.h b/services/sensorservice/SensorEventConnection.h
index 8f2d5db..9487a39 100644
--- a/services/sensorservice/SensorEventConnection.h
+++ b/services/sensorservice/SensorEventConnection.h
@@ -17,6 +17,7 @@
 #ifndef ANDROID_SENSOR_EVENT_CONNECTION_H
 #define ANDROID_SENSOR_EVENT_CONNECTION_H
 
+#include <atomic>
 #include <stdint.h>
 #include <sys/types.h>
 #include <unordered_map>
@@ -182,8 +183,8 @@
     int mTotalAcksNeeded, mTotalAcksReceived;
 #endif
 
-    mutable Mutex mDestroyLock;
-    bool mDestroyed;
+    // Used to track if this object was inappropriately used after destroy().
+    std::atomic_bool mDestroyed;
 
     // Store a mapping of sensor handles to required AppOp for a sensor. This map only contains a
     // valid mapping for sensors that require a permission in order to reduce the lookup time.
diff --git a/services/surfaceflinger/BufferLayer.cpp b/services/surfaceflinger/BufferLayer.cpp
index cf60b71..c77298e 100644
--- a/services/surfaceflinger/BufferLayer.cpp
+++ b/services/surfaceflinger/BufferLayer.cpp
@@ -366,7 +366,7 @@
         mFrameTracker.setActualPresentFence(std::shared_ptr<FenceTime>(presentFence));
     } else if (!display) {
         // Do nothing.
-    } else if (const auto displayId = display->getId();
+    } else if (const auto displayId = PhysicalDisplayId::tryCast(display->getId());
                displayId && mFlinger->getHwComposer().isConnected(*displayId)) {
         // The HWC doesn't support present fences, so use the refresh
         // timestamp instead.
diff --git a/services/surfaceflinger/BufferQueueLayer.cpp b/services/surfaceflinger/BufferQueueLayer.cpp
index a574549..0863a22 100644
--- a/services/surfaceflinger/BufferQueueLayer.cpp
+++ b/services/surfaceflinger/BufferQueueLayer.cpp
@@ -340,7 +340,7 @@
                                                FrameTracer::FrameEvent::LATCH);
 
         if (mQueueItems[0].surfaceFrame) {
-            mQueueItems[0].surfaceFrame->setActualEndTime(
+            mQueueItems[0].surfaceFrame->setAcquireFenceTime(
                     mQueueItems[0].item.mFenceTime->getSignalTime());
             mFlinger->mFrameTimeline->addSurfaceFrame(std::move(mQueueItems[0].surfaceFrame),
                                                       PresentState::Presented);
diff --git a/services/surfaceflinger/BufferStateLayer.cpp b/services/surfaceflinger/BufferStateLayer.cpp
index 2033f8e..361c1f3 100644
--- a/services/surfaceflinger/BufferStateLayer.cpp
+++ b/services/surfaceflinger/BufferStateLayer.cpp
@@ -162,8 +162,8 @@
     mCurrentStateModified = mCurrentState.modified;
     bool stateUpdateAvailable = Layer::applyPendingStates(stateToCommit);
     if (stateUpdateAvailable && mCallbackHandleAcquireTime != -1) {
-        // Update the actual end time if we have a buffer
-        mSurfaceFrame->setActualEndTime(mCallbackHandleAcquireTime);
+        // Update the acquire fence time if we have a buffer
+        mSurfaceFrame->setAcquireFenceTime(mCallbackHandleAcquireTime);
     }
     mCurrentStateModified = stateUpdateAvailable && mCurrentStateModified;
     mCurrentState.modified = false;
diff --git a/services/surfaceflinger/CompositionEngine/include/compositionengine/Display.h b/services/surfaceflinger/CompositionEngine/include/compositionengine/Display.h
index a38d1f3..01dd534 100644
--- a/services/surfaceflinger/CompositionEngine/include/compositionengine/Display.h
+++ b/services/surfaceflinger/CompositionEngine/include/compositionengine/Display.h
@@ -34,8 +34,8 @@
  */
 class Display : public virtual Output {
 public:
-    // Gets the HWC DisplayId for the display if there is one
-    virtual const std::optional<DisplayId>& getId() const = 0;
+    // Gets the DisplayId for the display
+    virtual DisplayId getId() const = 0;
 
     // True if the display is secure
     virtual bool isSecure() const = 0;
diff --git a/services/surfaceflinger/CompositionEngine/include/compositionengine/DisplayCreationArgs.h b/services/surfaceflinger/CompositionEngine/include/compositionengine/DisplayCreationArgs.h
index 6bc677d..95ba9f0 100644
--- a/services/surfaceflinger/CompositionEngine/include/compositionengine/DisplayCreationArgs.h
+++ b/services/surfaceflinger/CompositionEngine/include/compositionengine/DisplayCreationArgs.h
@@ -20,12 +20,14 @@
 #include <optional>
 #include <string>
 
+#include <ui/DisplayId.h>
 #include <ui/DisplayInfo.h>
 #include <ui/PixelFormat.h>
 #include <ui/Size.h>
 
 #include "DisplayHardware/DisplayIdentification.h"
 #include "DisplayHardware/PowerAdvisor.h"
+#include "DisplayIdGenerator.h"
 
 namespace android::compositionengine {
 
@@ -65,6 +67,9 @@
 
     // Debugging. Human readable name for the display.
     std::string name;
+
+    // Generator for IDs of virtual displays, which are backed by the GPU.
+    DisplayIdGenerator<GpuVirtualDisplayId>* gpuVirtualDisplayIdGenerator;
 };
 
 /**
@@ -95,6 +100,12 @@
         return *this;
     }
 
+    DisplayCreationArgsBuilder& setGpuVirtualDisplayIdGenerator(
+            DisplayIdGenerator<GpuVirtualDisplayId>& generator) {
+        mArgs.gpuVirtualDisplayIdGenerator = &generator;
+        return *this;
+    }
+
     DisplayCreationArgsBuilder& setIsSecure(bool isSecure) {
         mArgs.isSecure = isSecure;
         return *this;
diff --git a/services/surfaceflinger/CompositionEngine/include/compositionengine/impl/Display.h b/services/surfaceflinger/CompositionEngine/include/compositionengine/impl/Display.h
index 7a4f738..54e91ae 100644
--- a/services/surfaceflinger/CompositionEngine/include/compositionengine/impl/Display.h
+++ b/services/surfaceflinger/CompositionEngine/include/compositionengine/impl/Display.h
@@ -57,7 +57,7 @@
     void finishFrame(const CompositionRefreshArgs&) override;
 
     // compositionengine::Display overrides
-    const std::optional<DisplayId>& getId() const override;
+    DisplayId getId() const override;
     bool isSecure() const override;
     bool isVirtual() const override;
     void disconnect() override;
@@ -85,12 +85,14 @@
     std::unique_ptr<compositionengine::OutputLayer> createOutputLayer(const sp<LayerFE>&) const;
 
     // Testing
-    void setDisplayIdForTesting(std::optional<DisplayId> displayId);
+    void setDisplayIdForTesting(DisplayId displayId);
 
 private:
     bool mIsVirtual = false;
-    std::optional<DisplayId> mId;
+    bool mIsDisconnected = false;
+    DisplayId mId;
     Hwc2::PowerAdvisor* mPowerAdvisor = nullptr;
+    DisplayIdGenerator<GpuVirtualDisplayId>* mGpuVirtualDisplayIdGenerator;
 };
 
 // This template factory function standardizes the implementation details of the
diff --git a/services/surfaceflinger/CompositionEngine/include/compositionengine/mock/Display.h b/services/surfaceflinger/CompositionEngine/include/compositionengine/mock/Display.h
index 3a4c70f..08a8b84 100644
--- a/services/surfaceflinger/CompositionEngine/include/compositionengine/mock/Display.h
+++ b/services/surfaceflinger/CompositionEngine/include/compositionengine/mock/Display.h
@@ -32,7 +32,7 @@
     Display();
     virtual ~Display();
 
-    MOCK_CONST_METHOD0(getId, const std::optional<DisplayId>&());
+    MOCK_CONST_METHOD0(getId, DisplayId());
     MOCK_CONST_METHOD0(isSecure, bool());
     MOCK_CONST_METHOD0(isVirtual, bool());
 
diff --git a/services/surfaceflinger/CompositionEngine/src/Display.cpp b/services/surfaceflinger/CompositionEngine/src/Display.cpp
index 5459861..0b0b8d5 100644
--- a/services/surfaceflinger/CompositionEngine/src/Display.cpp
+++ b/services/surfaceflinger/CompositionEngine/src/Display.cpp
@@ -51,19 +51,26 @@
 
 void Display::setConfiguration(const compositionengine::DisplayCreationArgs& args) {
     mIsVirtual = !args.physical;
-    mId = args.physical ? std::make_optional(args.physical->id) : std::nullopt;
     mPowerAdvisor = args.powerAdvisor;
-
     editState().isSecure = args.isSecure;
     editState().displaySpace.bounds = Rect(args.pixels);
-
     setLayerStackFilter(args.layerStackId,
-                        args.physical ? args.physical->type == DisplayConnectionType::Internal
-                                      : false);
+                        args.physical && args.physical->type == DisplayConnectionType::Internal);
     setName(args.name);
+    mGpuVirtualDisplayIdGenerator = args.gpuVirtualDisplayIdGenerator;
 
-    if (!args.physical && args.useHwcVirtualDisplays) {
-        mId = maybeAllocateDisplayIdForVirtualDisplay(args.pixels, args.pixelFormat);
+    if (args.physical) {
+        mId = args.physical->id;
+    } else {
+        std::optional<DisplayId> id;
+        if (args.useHwcVirtualDisplays) {
+            id = maybeAllocateDisplayIdForVirtualDisplay(args.pixels, args.pixelFormat);
+        }
+        if (!id) {
+            id = mGpuVirtualDisplayIdGenerator->nextId();
+        }
+        LOG_ALWAYS_FATAL_IF(!id, "Failed to generate display ID");
+        mId = *id;
     }
 }
 
@@ -78,7 +85,7 @@
     return Output::isValid() && mPowerAdvisor;
 }
 
-const std::optional<DisplayId>& Display::getId() const {
+DisplayId Display::getId() const {
     return mId;
 }
 
@@ -94,31 +101,36 @@
     return mId;
 }
 
-void Display::setDisplayIdForTesting(std::optional<DisplayId> displayId) {
+void Display::setDisplayIdForTesting(DisplayId displayId) {
     mId = displayId;
 }
 
 void Display::disconnect() {
-    if (!mId) {
+    if (mIsDisconnected) {
         return;
     }
 
-    auto& hwc = getCompositionEngine().getHwComposer();
-    hwc.disconnectDisplay(*mId);
-    mId.reset();
+    mIsDisconnected = true;
+    if (const auto id = GpuVirtualDisplayId::tryCast(mId)) {
+        mGpuVirtualDisplayIdGenerator->markUnused(*id);
+        return;
+    }
+    const auto halDisplayId = HalDisplayId::tryCast(mId);
+    LOG_FATAL_IF(!halDisplayId);
+    getCompositionEngine().getHwComposer().disconnectDisplay(*halDisplayId);
 }
 
 void Display::setColorTransform(const compositionengine::CompositionRefreshArgs& args) {
     Output::setColorTransform(args);
-
-    if (!mId || CC_LIKELY(!args.colorTransformMatrix)) {
+    const auto halDisplayId = HalDisplayId::tryCast(mId);
+    if (mIsDisconnected || !halDisplayId || CC_LIKELY(!args.colorTransformMatrix)) {
         return;
     }
 
     auto& hwc = getCompositionEngine().getHwComposer();
-    status_t result = hwc.setColorTransform(*mId, *args.colorTransformMatrix);
+    status_t result = hwc.setColorTransform(*halDisplayId, *args.colorTransformMatrix);
     ALOGE_IF(result != NO_ERROR, "Failed to set color transform on display \"%s\": %d",
-             mId ? to_string(*mId).c_str() : "", result);
+             to_string(mId).c_str(), result);
 }
 
 void Display::setColorProfile(const ColorProfile& colorProfile) {
@@ -140,8 +152,10 @@
 
     Output::setColorProfile(colorProfile);
 
-    auto& hwc = getCompositionEngine().getHwComposer();
-    hwc.setActiveColorMode(*mId, colorProfile.mode, colorProfile.renderIntent);
+    const auto physicalId = PhysicalDisplayId::tryCast(mId);
+    LOG_FATAL_IF(!physicalId);
+    getCompositionEngine().getHwComposer().setActiveColorMode(*physicalId, colorProfile.mode,
+                                                              colorProfile.renderIntent);
 }
 
 void Display::dump(std::string& out) const {
@@ -150,14 +164,8 @@
     StringAppendF(&out, "   Composition Display State: [\"%s\"]", getName().c_str());
 
     out.append("\n   ");
-
     dumpVal(out, "isVirtual", mIsVirtual);
-    if (mId) {
-        dumpVal(out, "hwcId", to_string(*mId));
-    } else {
-        StringAppendF(&out, "no hwcId, ");
-    }
-
+    dumpVal(out, "DisplayId", to_string(mId));
     out.append("\n");
 
     Output::dumpBase(out);
@@ -178,31 +186,33 @@
 
 std::unique_ptr<compositionengine::OutputLayer> Display::createOutputLayer(
         const sp<compositionengine::LayerFE>& layerFE) const {
-    auto result = impl::createOutputLayer(*this, layerFE);
+    auto outputLayer = impl::createOutputLayer(*this, layerFE);
 
-    if (result && mId) {
+    if (const auto halDisplayId = HalDisplayId::tryCast(mId);
+        outputLayer && !mIsDisconnected && halDisplayId) {
         auto& hwc = getCompositionEngine().getHwComposer();
-        auto displayId = *mId;
         // Note: For the moment we ensure it is safe to take a reference to the
         // HWComposer implementation by destroying all the OutputLayers (and
         // hence the HWC2::Layers they own) before setting a new HWComposer. See
         // for example SurfaceFlinger::updateVrFlinger().
         // TODO(b/121291683): Make this safer.
-        auto hwcLayer = std::shared_ptr<HWC2::Layer>(hwc.createLayer(displayId),
-                                                     [&hwc, displayId](HWC2::Layer* layer) {
-                                                         hwc.destroyLayer(displayId, layer);
-                                                     });
+        auto hwcLayer =
+                std::shared_ptr<HWC2::Layer>(hwc.createLayer(*halDisplayId),
+                                             [&hwc, id = *halDisplayId](HWC2::Layer* layer) {
+                                                 hwc.destroyLayer(id, layer);
+                                             });
         ALOGE_IF(!hwcLayer, "Failed to create a HWC layer for a HWC supported display %s",
                  getName().c_str());
-        result->setHwcLayer(std::move(hwcLayer));
+        outputLayer->setHwcLayer(std::move(hwcLayer));
     }
-    return result;
+    return outputLayer;
 }
 
 void Display::setReleasedLayers(const compositionengine::CompositionRefreshArgs& refreshArgs) {
     Output::setReleasedLayers(refreshArgs);
 
-    if (!mId || refreshArgs.layersWithQueuedFrames.empty()) {
+    if (mIsDisconnected || GpuVirtualDisplayId::tryCast(mId) ||
+        refreshArgs.layersWithQueuedFrames.empty()) {
         return;
     }
 
@@ -238,19 +248,25 @@
     ATRACE_CALL();
     ALOGV(__FUNCTION__);
 
+    if (mIsDisconnected) {
+        return;
+    }
+
     // Default to the base settings -- client composition only.
     Output::chooseCompositionStrategy();
 
-    // If we don't have a HWC display, then we are done
-    if (!mId) {
+    // If we don't have a HWC display, then we are done.
+    const auto halDisplayId = HalDisplayId::tryCast(mId);
+    if (!halDisplayId) {
         return;
     }
 
     // Get any composition changes requested by the HWC device, and apply them.
     std::optional<android::HWComposer::DeviceRequestedChanges> changes;
     auto& hwc = getCompositionEngine().getHwComposer();
-    if (status_t result = hwc.getDeviceCompositionChanges(*mId, anyLayersRequireClientComposition(),
-                                                          &changes);
+    if (status_t result =
+                hwc.getDeviceCompositionChanges(*halDisplayId, anyLayersRequireClientComposition(),
+                                                &changes);
         result != NO_ERROR) {
         ALOGE("chooseCompositionStrategy failed for %s: %d (%s)", getName().c_str(), result,
               strerror(-result));
@@ -271,8 +287,12 @@
 
 bool Display::getSkipColorTransform() const {
     const auto& hwc = getCompositionEngine().getHwComposer();
-    return mId ? hwc.hasDisplayCapability(*mId, hal::DisplayCapability::SKIP_CLIENT_COLOR_TRANSFORM)
-               : hwc.hasCapability(hal::Capability::SKIP_CLIENT_COLOR_TRANSFORM);
+    if (const auto halDisplayId = HalDisplayId::tryCast(mId)) {
+        return hwc.hasDisplayCapability(*halDisplayId,
+                                        hal::DisplayCapability::SKIP_CLIENT_COLOR_TRANSFORM);
+    }
+
+    return hwc.hasCapability(hal::Capability::SKIP_CLIENT_COLOR_TRANSFORM);
 }
 
 bool Display::anyLayersRequireClientComposition() const {
@@ -339,16 +359,17 @@
 }
 
 compositionengine::Output::FrameFences Display::presentAndGetFrameFences() {
-    auto result = impl::Output::presentAndGetFrameFences();
+    auto fences = impl::Output::presentAndGetFrameFences();
 
-    if (!mId) {
-        return result;
+    const auto halDisplayIdOpt = HalDisplayId::tryCast(mId);
+    if (mIsDisconnected || !halDisplayIdOpt) {
+        return fences;
     }
 
     auto& hwc = getCompositionEngine().getHwComposer();
-    hwc.presentAndGetReleaseFences(*mId);
+    hwc.presentAndGetReleaseFences(*halDisplayIdOpt);
 
-    result.presentFence = hwc.getPresentFence(*mId);
+    fences.presentFence = hwc.getPresentFence(*halDisplayIdOpt);
 
     // TODO(b/121291683): Change HWComposer call to return entire map
     for (const auto* layer : getOutputLayersOrderedByZ()) {
@@ -357,19 +378,19 @@
             continue;
         }
 
-        result.layerFences.emplace(hwcLayer, hwc.getLayerReleaseFence(*mId, hwcLayer));
+        fences.layerFences.emplace(hwcLayer, hwc.getLayerReleaseFence(*halDisplayIdOpt, hwcLayer));
     }
 
-    hwc.clearReleaseFences(*mId);
+    hwc.clearReleaseFences(*halDisplayIdOpt);
 
-    return result;
+    return fences;
 }
 
 void Display::setExpensiveRenderingExpected(bool enabled) {
     Output::setExpensiveRenderingExpected(enabled);
 
-    if (mPowerAdvisor && mId) {
-        mPowerAdvisor->setExpensiveRenderingExpected(*mId, enabled);
+    if (mPowerAdvisor && !GpuVirtualDisplayId::tryCast(mId)) {
+        mPowerAdvisor->setExpensiveRenderingExpected(mId, enabled);
     }
 }
 
@@ -378,11 +399,10 @@
     // 1) It is being handled by hardware composer, which may need this to
     //    keep its virtual display state machine in sync, or
     // 2) There is work to be done (the dirty region isn't empty)
-    if (!mId) {
-        if (getDirtyRegion(refreshArgs.repaintEverything).isEmpty()) {
-            ALOGV("Skipping display composition");
-            return;
-        }
+    if (GpuVirtualDisplayId::tryCast(mId) &&
+        getDirtyRegion(refreshArgs.repaintEverything).isEmpty()) {
+        ALOGV("Skipping display composition");
+        return;
     }
 
     impl::Output::finishFrame(refreshArgs);
diff --git a/services/surfaceflinger/CompositionEngine/tests/DisplayTest.cpp b/services/surfaceflinger/CompositionEngine/tests/DisplayTest.cpp
index 4519a9d..6d01bf1 100644
--- a/services/surfaceflinger/CompositionEngine/tests/DisplayTest.cpp
+++ b/services/surfaceflinger/CompositionEngine/tests/DisplayTest.cpp
@@ -176,6 +176,7 @@
     DisplayCreationArgs getDisplayCreationArgsForNonHWCVirtualDisplay() {
         return DisplayCreationArgsBuilder()
                 .setUseHwcVirtualDisplays(false)
+                .setGpuVirtualDisplayIdGenerator(mGpuDisplayIdGenerator)
                 .setPixels({DEFAULT_DISPLAY_WIDTH, DEFAULT_DISPLAY_HEIGHT})
                 .setPixelFormat(static_cast<ui::PixelFormat>(PIXEL_FORMAT_RGBA_8888))
                 .setIsSecure(false)
@@ -189,6 +190,7 @@
     StrictMock<renderengine::mock::RenderEngine> mRenderEngine;
     StrictMock<mock::CompositionEngine> mCompositionEngine;
     sp<mock::NativeWindow> mNativeWindow = new StrictMock<mock::NativeWindow>();
+    RandomDisplayIdGenerator<GpuVirtualDisplayId> mGpuDisplayIdGenerator;
 };
 
 struct PartialMockDisplayTestCommon : public DisplayTestCommon {
@@ -245,7 +247,7 @@
                                        getDisplayCreationArgsForNonHWCVirtualDisplay());
     EXPECT_FALSE(display->isSecure());
     EXPECT_TRUE(display->isVirtual());
-    EXPECT_EQ(std::nullopt, display->getId());
+    EXPECT_TRUE(GpuVirtualDisplayId::tryCast(display->getId()));
 }
 
 /*
@@ -332,6 +334,7 @@
     mDisplay->setConfiguration(
             DisplayCreationArgsBuilder()
                     .setUseHwcVirtualDisplays(true)
+                    .setGpuVirtualDisplayIdGenerator(mGpuDisplayIdGenerator)
                     .setPixels(ui::Size(DEFAULT_DISPLAY_WIDTH, DEFAULT_DISPLAY_WIDTH))
                     .setPixelFormat(static_cast<ui::PixelFormat>(PIXEL_FORMAT_RGBA_8888))
                     .setIsSecure(false)
@@ -340,7 +343,7 @@
                     .setName(getDisplayNameFromCurrentTest())
                     .build());
 
-    EXPECT_EQ(std::nullopt, mDisplay->getId());
+    EXPECT_TRUE(GpuVirtualDisplayId::tryCast(mDisplay->getId()));
     EXPECT_FALSE(mDisplay->isSecure());
     EXPECT_TRUE(mDisplay->isVirtual());
     EXPECT_EQ(DEFAULT_LAYER_STACK, mDisplay->getState().layerStackId);
@@ -352,6 +355,7 @@
     mDisplay->setConfiguration(
             DisplayCreationArgsBuilder()
                     .setUseHwcVirtualDisplays(false)
+                    .setGpuVirtualDisplayIdGenerator(mGpuDisplayIdGenerator)
                     .setPixels(ui::Size(DEFAULT_DISPLAY_WIDTH, DEFAULT_DISPLAY_WIDTH))
                     .setPixelFormat(static_cast<ui::PixelFormat>(PIXEL_FORMAT_RGBA_8888))
                     .setIsSecure(false)
@@ -360,7 +364,7 @@
                     .setName(getDisplayNameFromCurrentTest())
                     .build());
 
-    EXPECT_EQ(std::nullopt, mDisplay->getId());
+    EXPECT_TRUE(GpuVirtualDisplayId::tryCast(mDisplay->getId()));
     EXPECT_FALSE(mDisplay->isSecure());
     EXPECT_TRUE(mDisplay->isVirtual());
     EXPECT_EQ(DEFAULT_LAYER_STACK, mDisplay->getState().layerStackId);
@@ -375,16 +379,13 @@
 using DisplayDisconnectTest = PartialMockDisplayTestCommon;
 
 TEST_F(DisplayDisconnectTest, disconnectsDisplay) {
-    // The first call to disconnect will disconnect the display with the HWC and
-    // set mHwcId to -1.
-    EXPECT_CALL(mHwComposer, disconnectDisplay(DEFAULT_DISPLAY_ID)).Times(1);
+    // The first call to disconnect will disconnect the display with the HWC.
+    EXPECT_CALL(mHwComposer, disconnectDisplay(HalDisplayId(DEFAULT_DISPLAY_ID))).Times(1);
     mDisplay->disconnect();
-    EXPECT_FALSE(mDisplay->getId());
 
     // Subsequent calls will do nothing,
-    EXPECT_CALL(mHwComposer, disconnectDisplay(DEFAULT_DISPLAY_ID)).Times(0);
+    EXPECT_CALL(mHwComposer, disconnectDisplay(HalDisplayId(DEFAULT_DISPLAY_ID))).Times(0);
     mDisplay->disconnect();
-    EXPECT_FALSE(mDisplay->getId());
 }
 
 /*
@@ -402,7 +403,8 @@
     // Identity matrix sets an identity state value
     const mat4 kIdentity;
 
-    EXPECT_CALL(mHwComposer, setColorTransform(DEFAULT_DISPLAY_ID, kIdentity)).Times(1);
+    EXPECT_CALL(mHwComposer, setColorTransform(HalDisplayId(DEFAULT_DISPLAY_ID), kIdentity))
+            .Times(1);
 
     refreshArgs.colorTransformMatrix = kIdentity;
     mDisplay->setColorTransform(refreshArgs);
@@ -410,7 +412,8 @@
     // Non-identity matrix sets a non-identity state value
     const mat4 kNonIdentity = mat4() * 2;
 
-    EXPECT_CALL(mHwComposer, setColorTransform(DEFAULT_DISPLAY_ID, kNonIdentity)).Times(1);
+    EXPECT_CALL(mHwComposer, setColorTransform(HalDisplayId(DEFAULT_DISPLAY_ID), kNonIdentity))
+            .Times(1);
 
     refreshArgs.colorTransformMatrix = kNonIdentity;
     mDisplay->setColorTransform(refreshArgs);
@@ -527,13 +530,14 @@
     sp<mock::LayerFE> layerFE = new StrictMock<mock::LayerFE>();
     StrictMock<HWC2::mock::Layer> hwcLayer;
 
-    EXPECT_CALL(mHwComposer, createLayer(DEFAULT_DISPLAY_ID)).WillOnce(Return(&hwcLayer));
+    EXPECT_CALL(mHwComposer, createLayer(HalDisplayId(DEFAULT_DISPLAY_ID)))
+            .WillOnce(Return(&hwcLayer));
 
     auto outputLayer = mDisplay->createOutputLayer(layerFE);
 
     EXPECT_EQ(&hwcLayer, outputLayer->getHwcLayer());
 
-    EXPECT_CALL(mHwComposer, destroyLayer(DEFAULT_DISPLAY_ID, &hwcLayer));
+    EXPECT_CALL(mHwComposer, destroyLayer(HalDisplayId(DEFAULT_DISPLAY_ID), &hwcLayer));
     outputLayer.reset();
 }
 
@@ -606,7 +610,7 @@
     auto args = getDisplayCreationArgsForNonHWCVirtualDisplay();
     std::shared_ptr<Display> nonHwcDisplay =
             createPartialMockDisplay<Display>(mCompositionEngine, args);
-    EXPECT_FALSE(nonHwcDisplay->getId());
+    EXPECT_TRUE(GpuVirtualDisplayId::tryCast(nonHwcDisplay->getId()));
 
     nonHwcDisplay->chooseCompositionStrategy();
 
@@ -617,7 +621,8 @@
 
 TEST_F(DisplayChooseCompositionStrategyTest, takesEarlyOutOnHwcError) {
     EXPECT_CALL(*mDisplay, anyLayersRequireClientComposition()).WillOnce(Return(false));
-    EXPECT_CALL(mHwComposer, getDeviceCompositionChanges(DEFAULT_DISPLAY_ID, false, _))
+    EXPECT_CALL(mHwComposer,
+                getDeviceCompositionChanges(HalDisplayId(DEFAULT_DISPLAY_ID), false, _))
             .WillOnce(Return(INVALID_OPERATION));
 
     mDisplay->chooseCompositionStrategy();
@@ -639,7 +644,7 @@
             .InSequence(s)
             .WillOnce(Return(false));
 
-    EXPECT_CALL(mHwComposer, getDeviceCompositionChanges(DEFAULT_DISPLAY_ID, true, _))
+    EXPECT_CALL(mHwComposer, getDeviceCompositionChanges(HalDisplayId(DEFAULT_DISPLAY_ID), true, _))
             .WillOnce(Return(NO_ERROR));
     EXPECT_CALL(*mDisplay, allLayersRequireClientComposition()).WillOnce(Return(false));
 
@@ -669,7 +674,7 @@
             .InSequence(s)
             .WillOnce(Return(false));
 
-    EXPECT_CALL(mHwComposer, getDeviceCompositionChanges(DEFAULT_DISPLAY_ID, true, _))
+    EXPECT_CALL(mHwComposer, getDeviceCompositionChanges(HalDisplayId(DEFAULT_DISPLAY_ID), true, _))
             .WillOnce(DoAll(SetArgPointee<2>(changes), Return(NO_ERROR)));
     EXPECT_CALL(*mDisplay, applyChangedTypesToLayers(changes.changedTypes)).Times(1);
     EXPECT_CALL(*mDisplay, applyDisplayRequests(changes.displayRequests)).Times(1);
@@ -699,7 +704,7 @@
 
 TEST_F(DisplayGetSkipColorTransformTest, checksDisplayCapability) {
     EXPECT_CALL(mHwComposer,
-                hasDisplayCapability(DEFAULT_DISPLAY_ID,
+                hasDisplayCapability(HalDisplayId(DEFAULT_DISPLAY_ID),
                                      hal::DisplayCapability::SKIP_CLIENT_COLOR_TRANSFORM))
             .WillOnce(Return(true));
     EXPECT_TRUE(mDisplay->getSkipColorTransform());
@@ -857,13 +862,16 @@
     sp<Fence> layer1Fence = new Fence();
     sp<Fence> layer2Fence = new Fence();
 
-    EXPECT_CALL(mHwComposer, presentAndGetReleaseFences(DEFAULT_DISPLAY_ID)).Times(1);
-    EXPECT_CALL(mHwComposer, getPresentFence(DEFAULT_DISPLAY_ID)).WillOnce(Return(presentFence));
-    EXPECT_CALL(mHwComposer, getLayerReleaseFence(DEFAULT_DISPLAY_ID, &mLayer1.hwc2Layer))
+    EXPECT_CALL(mHwComposer, presentAndGetReleaseFences(HalDisplayId(DEFAULT_DISPLAY_ID))).Times(1);
+    EXPECT_CALL(mHwComposer, getPresentFence(HalDisplayId(DEFAULT_DISPLAY_ID)))
+            .WillOnce(Return(presentFence));
+    EXPECT_CALL(mHwComposer,
+                getLayerReleaseFence(HalDisplayId(DEFAULT_DISPLAY_ID), &mLayer1.hwc2Layer))
             .WillOnce(Return(layer1Fence));
-    EXPECT_CALL(mHwComposer, getLayerReleaseFence(DEFAULT_DISPLAY_ID, &mLayer2.hwc2Layer))
+    EXPECT_CALL(mHwComposer,
+                getLayerReleaseFence(HalDisplayId(DEFAULT_DISPLAY_ID), &mLayer2.hwc2Layer))
             .WillOnce(Return(layer2Fence));
-    EXPECT_CALL(mHwComposer, clearReleaseFences(DEFAULT_DISPLAY_ID)).Times(1);
+    EXPECT_CALL(mHwComposer, clearReleaseFences(HalDisplayId(DEFAULT_DISPLAY_ID))).Times(1);
 
     auto result = mDisplay->presentAndGetFrameFences();
 
diff --git a/services/surfaceflinger/CompositionEngine/tests/MockHWComposer.h b/services/surfaceflinger/CompositionEngine/tests/MockHWComposer.h
index 1dd5df4..b5cda68 100644
--- a/services/surfaceflinger/CompositionEngine/tests/MockHWComposer.h
+++ b/services/surfaceflinger/CompositionEngine/tests/MockHWComposer.h
@@ -42,63 +42,68 @@
     MOCK_CONST_METHOD3(getDisplayIdentificationData,
                        bool(hal::HWDisplayId, uint8_t*, DisplayIdentificationData*));
     MOCK_CONST_METHOD1(hasCapability, bool(hal::Capability));
-    MOCK_CONST_METHOD2(hasDisplayCapability, bool(DisplayId, hal::DisplayCapability));
+    MOCK_CONST_METHOD2(hasDisplayCapability, bool(HalDisplayId, hal::DisplayCapability));
 
     MOCK_METHOD3(allocateVirtualDisplay,
                  std::optional<DisplayId>(uint32_t, uint32_t, ui::PixelFormat*));
     MOCK_METHOD2(allocatePhysicalDisplay, void(hal::HWDisplayId, PhysicalDisplayId));
-    MOCK_METHOD1(createLayer, HWC2::Layer*(DisplayId));
-    MOCK_METHOD2(destroyLayer, void(DisplayId, HWC2::Layer*));
+    MOCK_METHOD1(createLayer, HWC2::Layer*(HalDisplayId));
+    MOCK_METHOD2(destroyLayer, void(HalDisplayId, HWC2::Layer*));
     MOCK_METHOD3(getDeviceCompositionChanges,
-                 status_t(DisplayId, bool,
+                 status_t(HalDisplayId, bool,
                           std::optional<android::HWComposer::DeviceRequestedChanges>*));
     MOCK_METHOD5(setClientTarget,
-                 status_t(DisplayId, uint32_t, const sp<Fence>&, const sp<GraphicBuffer>&,
+                 status_t(HalDisplayId, uint32_t, const sp<Fence>&, const sp<GraphicBuffer>&,
                           ui::Dataspace));
-    MOCK_METHOD1(presentAndGetReleaseFences, status_t(DisplayId));
-    MOCK_METHOD2(setPowerMode, status_t(DisplayId, hal::PowerMode));
-    MOCK_METHOD2(setActiveConfig, status_t(DisplayId, size_t));
-    MOCK_METHOD2(setColorTransform, status_t(DisplayId, const mat4&));
-    MOCK_METHOD1(disconnectDisplay, void(DisplayId));
+    MOCK_METHOD1(presentAndGetReleaseFences, status_t(HalDisplayId));
+    MOCK_METHOD2(setPowerMode, status_t(PhysicalDisplayId, hal::PowerMode));
+    MOCK_METHOD2(setActiveConfig, status_t(HalDisplayId, size_t));
+    MOCK_METHOD2(setColorTransform, status_t(HalDisplayId, const mat4&));
+    MOCK_METHOD1(disconnectDisplay, void(HalDisplayId));
     MOCK_CONST_METHOD1(hasDeviceComposition, bool(const std::optional<DisplayId>&));
-    MOCK_CONST_METHOD1(getPresentFence, sp<Fence>(DisplayId));
-    MOCK_CONST_METHOD2(getLayerReleaseFence, sp<Fence>(DisplayId, HWC2::Layer*));
-    MOCK_METHOD3(setOutputBuffer, status_t(DisplayId, const sp<Fence>&, const sp<GraphicBuffer>&));
-    MOCK_METHOD1(clearReleaseFences, void(DisplayId));
-    MOCK_METHOD2(getHdrCapabilities, status_t(DisplayId, HdrCapabilities*));
-    MOCK_CONST_METHOD1(getSupportedPerFrameMetadata, int32_t(DisplayId));
-    MOCK_CONST_METHOD2(getRenderIntents, std::vector<ui::RenderIntent>(DisplayId, ui::ColorMode));
-    MOCK_METHOD2(getDataspaceSaturationMatrix, mat4(DisplayId, ui::Dataspace));
+    MOCK_CONST_METHOD1(getPresentFence, sp<Fence>(HalDisplayId));
+    MOCK_CONST_METHOD2(getLayerReleaseFence, sp<Fence>(HalDisplayId, HWC2::Layer*));
+    MOCK_METHOD3(setOutputBuffer,
+                 status_t(HalVirtualDisplayId, const sp<Fence>&, const sp<GraphicBuffer>&));
+    MOCK_METHOD1(clearReleaseFences, void(HalDisplayId));
+    MOCK_METHOD2(getHdrCapabilities, status_t(HalDisplayId, HdrCapabilities*));
+    MOCK_CONST_METHOD1(getSupportedPerFrameMetadata, int32_t(HalDisplayId));
+    MOCK_CONST_METHOD2(getRenderIntents,
+                       std::vector<ui::RenderIntent>(HalDisplayId, ui::ColorMode));
+    MOCK_METHOD2(getDataspaceSaturationMatrix, mat4(HalDisplayId, ui::Dataspace));
     MOCK_METHOD4(getDisplayedContentSamplingAttributes,
-                 status_t(DisplayId, ui::PixelFormat*, ui::Dataspace*, uint8_t*));
-    MOCK_METHOD4(setDisplayContentSamplingEnabled, status_t(DisplayId, bool, uint8_t, uint64_t));
+                 status_t(HalDisplayId, ui::PixelFormat*, ui::Dataspace*, uint8_t*));
+    MOCK_METHOD4(setDisplayContentSamplingEnabled, status_t(HalDisplayId, bool, uint8_t, uint64_t));
     MOCK_METHOD4(getDisplayedContentSample,
-                 status_t(DisplayId, uint64_t, uint64_t, DisplayedFrameStats*));
-    MOCK_METHOD2(setDisplayBrightness, std::future<status_t>(DisplayId, float));
-    MOCK_METHOD2(getDisplayBrightnessSupport, status_t(DisplayId, bool*));
+                 status_t(HalDisplayId, uint64_t, uint64_t, DisplayedFrameStats*));
+    MOCK_METHOD2(setDisplayBrightness, std::future<status_t>(PhysicalDisplayId, float));
+    MOCK_METHOD2(getDisplayBrightnessSupport, status_t(PhysicalDisplayId, bool*));
 
     MOCK_METHOD2(onHotplug,
                  std::optional<DisplayIdentificationInfo>(hal::HWDisplayId, hal::Connection));
     MOCK_METHOD2(onVsync, bool(hal::HWDisplayId, int64_t));
-    MOCK_METHOD2(setVsyncEnabled, void(DisplayId, hal::Vsync));
-    MOCK_CONST_METHOD1(getRefreshTimestamp, nsecs_t(DisplayId));
-    MOCK_CONST_METHOD1(isConnected, bool(DisplayId));
-    MOCK_CONST_METHOD1(getConfigs,
-                       std::vector<std::shared_ptr<const HWC2::Display::Config>>(DisplayId));
-    MOCK_CONST_METHOD1(getActiveConfig, std::shared_ptr<const HWC2::Display::Config>(DisplayId));
-    MOCK_CONST_METHOD1(getActiveConfigIndex, int(DisplayId));
-    MOCK_CONST_METHOD1(getColorModes, std::vector<ui::ColorMode>(DisplayId));
-    MOCK_METHOD3(setActiveColorMode, status_t(DisplayId, ui::ColorMode, ui::RenderIntent));
+    MOCK_METHOD2(setVsyncEnabled, void(PhysicalDisplayId, hal::Vsync));
+    MOCK_CONST_METHOD1(getRefreshTimestamp, nsecs_t(PhysicalDisplayId));
+    MOCK_CONST_METHOD1(isConnected, bool(PhysicalDisplayId));
+    MOCK_CONST_METHOD1(
+            getConfigs,
+            std::vector<std::shared_ptr<const HWC2::Display::Config>>(PhysicalDisplayId));
+    MOCK_CONST_METHOD1(getActiveConfig,
+                       std::shared_ptr<const HWC2::Display::Config>(PhysicalDisplayId));
+    MOCK_CONST_METHOD1(getActiveConfigIndex, int(PhysicalDisplayId));
+    MOCK_CONST_METHOD1(getColorModes, std::vector<ui::ColorMode>(PhysicalDisplayId));
+    MOCK_METHOD3(setActiveColorMode, status_t(PhysicalDisplayId, ui::ColorMode, ui::RenderIntent));
     MOCK_CONST_METHOD0(isUsingVrComposer, bool());
-    MOCK_CONST_METHOD1(getDisplayConnectionType, DisplayConnectionType(DisplayId));
-    MOCK_CONST_METHOD1(isVsyncPeriodSwitchSupported, bool(DisplayId));
-    MOCK_CONST_METHOD1(getDisplayVsyncPeriod, nsecs_t(DisplayId));
+    MOCK_CONST_METHOD1(getDisplayConnectionType, DisplayConnectionType(PhysicalDisplayId));
+    MOCK_CONST_METHOD1(isVsyncPeriodSwitchSupported, bool(PhysicalDisplayId));
+    MOCK_CONST_METHOD1(getDisplayVsyncPeriod, nsecs_t(PhysicalDisplayId));
     MOCK_METHOD4(setActiveConfigWithConstraints,
-                 status_t(DisplayId, size_t, const hal::VsyncPeriodChangeConstraints&,
+                 status_t(PhysicalDisplayId, size_t, const hal::VsyncPeriodChangeConstraints&,
                           hal::VsyncPeriodChangeTimeline*));
-    MOCK_METHOD2(setAutoLowLatencyMode, status_t(DisplayId, bool));
-    MOCK_METHOD2(getSupportedContentTypes, status_t(DisplayId, std::vector<hal::ContentType>*));
-    MOCK_METHOD2(setContentType, status_t(DisplayId, hal::ContentType));
+    MOCK_METHOD2(setAutoLowLatencyMode, status_t(PhysicalDisplayId, bool));
+    MOCK_METHOD2(getSupportedContentTypes,
+                 status_t(PhysicalDisplayId, std::vector<hal::ContentType>*));
+    MOCK_METHOD2(setContentType, status_t(PhysicalDisplayId, hal::ContentType));
     MOCK_CONST_METHOD0(getSupportedLayerGenericMetadata,
                        const std::unordered_map<std::string, bool>&());
 
diff --git a/services/surfaceflinger/CompositionEngine/tests/RenderSurfaceTest.cpp b/services/surfaceflinger/CompositionEngine/tests/RenderSurfaceTest.cpp
index 8d1eb36..6ce8a6b 100644
--- a/services/surfaceflinger/CompositionEngine/tests/RenderSurfaceTest.cpp
+++ b/services/surfaceflinger/CompositionEngine/tests/RenderSurfaceTest.cpp
@@ -33,7 +33,7 @@
 
 constexpr int32_t DEFAULT_DISPLAY_WIDTH = 1920;
 constexpr int32_t DEFAULT_DISPLAY_HEIGHT = 1080;
-constexpr std::optional<DisplayId> DEFAULT_DISPLAY_ID = {PhysicalDisplayId(123u)};
+constexpr DisplayId DEFAULT_DISPLAY_ID = PhysicalDisplayId(123u);
 const std::string DEFAULT_DISPLAY_NAME = "Mock Display";
 
 using testing::_;
@@ -48,7 +48,7 @@
 class RenderSurfaceTest : public testing::Test {
 public:
     RenderSurfaceTest() {
-        EXPECT_CALL(mDisplay, getId()).WillRepeatedly(ReturnRef(DEFAULT_DISPLAY_ID));
+        EXPECT_CALL(mDisplay, getId()).WillRepeatedly(Return(DEFAULT_DISPLAY_ID));
         EXPECT_CALL(mDisplay, getName()).WillRepeatedly(ReturnRef(DEFAULT_DISPLAY_NAME));
         EXPECT_CALL(mCompositionEngine, getRenderEngine).WillRepeatedly(ReturnRef(mRenderEngine));
         EXPECT_CALL(*mNativeWindow, disconnect(NATIVE_WINDOW_API_EGL))
diff --git a/services/surfaceflinger/DisplayDevice.cpp b/services/surfaceflinger/DisplayDevice.cpp
index a1ccaad..5bd7a1f 100644
--- a/services/surfaceflinger/DisplayDevice.cpp
+++ b/services/surfaceflinger/DisplayDevice.cpp
@@ -168,22 +168,16 @@
         sPrimaryDisplayRotationFlags = ui::Transform::toRotationFlags(orientation);
     }
 
-    const Rect& displayBounds = getCompositionDisplay()->getState().displaySpace.bounds;
-    const int displayWidth = displayBounds.width();
-    const int displayHeight = displayBounds.height();
-
     if (!orientedDisplaySpaceRect.isValid()) {
-        // the destination frame can be invalid if it has never been set,
-        // in that case we assume the whole display frame.
-        orientedDisplaySpaceRect = Rect(displayWidth, displayHeight);
+        // The destination frame can be invalid if it has never been set,
+        // in that case we assume the whole display size.
+        orientedDisplaySpaceRect = getCompositionDisplay()->getState().displaySpace.bounds;
     }
 
     if (layerStackSpaceRect.isEmpty()) {
-        // layerStackSpaceRect can be invalid if it has never been set, in that case
-        // we assume the whole display size.
-        // It's also invalid to have an empty layerStackSpaceRect, so we handle that
-        // case in the same way.
-        layerStackSpaceRect = Rect(displayWidth, displayHeight);
+        // The layerStackSpaceRect can be invalid if it has never been set, in that case
+        // we assume the whole framebuffer size.
+        layerStackSpaceRect = getCompositionDisplay()->getState().framebufferSpace.bounds;
         if (orientation == ui::ROTATION_90 || orientation == ui::ROTATION_270) {
             std::swap(layerStackSpaceRect.right, layerStackSpaceRect.bottom);
         }
@@ -201,17 +195,12 @@
 }
 
 std::string DisplayDevice::getDebugName() const {
-    std::string displayId;
-    if (const auto id = getId()) {
-        displayId = to_string(*id) + ", ";
-    }
-
     const char* type = "virtual";
     if (mConnectionType) {
         type = *mConnectionType == DisplayConnectionType::Internal ? "internal" : "external";
     }
 
-    return base::StringPrintf("DisplayDevice{%s%s%s, \"%s\"}", displayId.c_str(), type,
+    return base::StringPrintf("DisplayDevice{%s, %s%s, \"%s\"}", to_string(getId()).c_str(), type,
                               isPrimary() ? ", primary" : "", mDisplayName.c_str());
 }
 
@@ -235,9 +224,7 @@
     return mCompositionDisplay->getDisplayColorProfile()->hasRenderIntent(intent);
 }
 
-// ----------------------------------------------------------------------------
-
-const std::optional<DisplayId>& DisplayDevice::getId() const {
+DisplayId DisplayDevice::getId() const {
     return mCompositionDisplay->getId();
 }
 
diff --git a/services/surfaceflinger/DisplayDevice.h b/services/surfaceflinger/DisplayDevice.h
index 35a8b62..fa684c0 100644
--- a/services/surfaceflinger/DisplayDevice.h
+++ b/services/surfaceflinger/DisplayDevice.h
@@ -27,6 +27,7 @@
 #include <math/mat4.h>
 #include <renderengine/RenderEngine.h>
 #include <system/window.h>
+#include <ui/DisplayId.h>
 #include <ui/DisplayInfo.h>
 #include <ui/DisplayState.h>
 #include <ui/GraphicTypes.h>
@@ -104,7 +105,15 @@
     bool needsFiltering() const;
     ui::LayerStack getLayerStack() const;
 
-    const std::optional<DisplayId>& getId() const;
+    // Returns the physical ID of this display. This function asserts the ID is physical and it
+    // shouldn't be called for other display types, e.g. virtual.
+    PhysicalDisplayId getPhysicalId() const {
+        const auto displayIdOpt = PhysicalDisplayId::tryCast(getId());
+        LOG_FATAL_IF(!displayIdOpt);
+        return *displayIdOpt;
+    }
+
+    DisplayId getId() const;
     const wp<IBinder>& getDisplayToken() const { return mDisplayToken; }
     int32_t getSequenceId() const { return mSequenceId; }
 
diff --git a/services/surfaceflinger/DisplayHardware/FramebufferSurface.cpp b/services/surfaceflinger/DisplayHardware/FramebufferSurface.cpp
index 4c3b3e5..14b54cd 100644
--- a/services/surfaceflinger/DisplayHardware/FramebufferSurface.cpp
+++ b/services/surfaceflinger/DisplayHardware/FramebufferSurface.cpp
@@ -56,7 +56,7 @@
  *
  */
 
-FramebufferSurface::FramebufferSurface(HWComposer& hwc, DisplayId displayId,
+FramebufferSurface::FramebufferSurface(HWComposer& hwc, PhysicalDisplayId displayId,
                                        const sp<IGraphicBufferConsumer>& consumer,
                                        uint32_t maxWidth, uint32_t maxHeight)
       : ConsumerBase(consumer),
diff --git a/services/surfaceflinger/DisplayHardware/FramebufferSurface.h b/services/surfaceflinger/DisplayHardware/FramebufferSurface.h
index a1859f3..759943a 100644
--- a/services/surfaceflinger/DisplayHardware/FramebufferSurface.h
+++ b/services/surfaceflinger/DisplayHardware/FramebufferSurface.h
@@ -23,6 +23,7 @@
 #include <compositionengine/DisplaySurface.h>
 #include <compositionengine/impl/HwcBufferCache.h>
 #include <gui/ConsumerBase.h>
+#include <ui/DisplayId.h>
 #include <ui/Size.h>
 
 #include "DisplayIdentification.h"
@@ -39,7 +40,7 @@
 
 class FramebufferSurface : public ConsumerBase, public compositionengine::DisplaySurface {
 public:
-    FramebufferSurface(HWComposer& hwc, DisplayId displayId,
+    FramebufferSurface(HWComposer& hwc, PhysicalDisplayId displayId,
                        const sp<IGraphicBufferConsumer>& consumer, uint32_t maxWidth,
                        uint32_t maxHeight);
 
@@ -69,7 +70,7 @@
     status_t nextBuffer(uint32_t& outSlot, sp<GraphicBuffer>& outBuffer,
             sp<Fence>& outFence, ui::Dataspace& outDataspace);
 
-    const DisplayId mDisplayId;
+    const PhysicalDisplayId mDisplayId;
 
     // Framebuffer size has a dimension limitation in pixels based on the graphics capabilities of
     // the device.
diff --git a/services/surfaceflinger/DisplayHardware/HWC2.h b/services/surfaceflinger/DisplayHardware/HWC2.h
index 1f03787..89df84b 100644
--- a/services/surfaceflinger/DisplayHardware/HWC2.h
+++ b/services/surfaceflinger/DisplayHardware/HWC2.h
@@ -240,15 +240,14 @@
 
 class Display : public HWC2::Display {
 public:
-    Display(android::Hwc2::Composer& composer,
-            const std::unordered_set<hal::Capability>& capabilities, hal::HWDisplayId id,
-            hal::DisplayType type);
+    Display(android::Hwc2::Composer&, const std::unordered_set<hal::Capability>&, hal::HWDisplayId,
+            hal::DisplayType);
     ~Display() override;
 
     // Required by HWC2
     hal::Error acceptChanges() override;
     hal::Error createLayer(Layer** outLayer) override;
-    hal::Error destroyLayer(Layer* layer) override;
+    hal::Error destroyLayer(Layer*) override;
     hal::Error getActiveConfig(std::shared_ptr<const Config>* outConfig) const override;
     hal::Error getActiveConfigIndex(int* outIndex) const override;
     hal::Error getChangedCompositionTypes(
@@ -258,8 +257,7 @@
     int32_t getSupportedPerFrameMetadata() const override;
     hal::Error getRenderIntents(hal::ColorMode colorMode,
                                 std::vector<hal::RenderIntent>* outRenderIntents) const override;
-    hal::Error getDataspaceSaturationMatrix(hal::Dataspace dataspace,
-                                            android::mat4* outMatrix) override;
+    hal::Error getDataspaceSaturationMatrix(hal::Dataspace, android::mat4* outMatrix) override;
 
     // Doesn't call into the HWC2 device, so no errors are possible
     std::vector<std::shared_ptr<const Config>> getConfigs() const override;
@@ -285,11 +283,11 @@
     hal::Error setClientTarget(uint32_t slot, const android::sp<android::GraphicBuffer>& target,
                                const android::sp<android::Fence>& acquireFence,
                                hal::Dataspace dataspace) override;
-    hal::Error setColorMode(hal::ColorMode mode, hal::RenderIntent renderIntent) override;
+    hal::Error setColorMode(hal::ColorMode, hal::RenderIntent) override;
     hal::Error setColorTransform(const android::mat4& matrix, hal::ColorTransform hint) override;
-    hal::Error setOutputBuffer(const android::sp<android::GraphicBuffer>& buffer,
+    hal::Error setOutputBuffer(const android::sp<android::GraphicBuffer>&,
                                const android::sp<android::Fence>& releaseFence) override;
-    hal::Error setPowerMode(hal::PowerMode mode) override;
+    hal::Error setPowerMode(hal::PowerMode) override;
     hal::Error setVsyncEnabled(hal::Vsync enabled) override;
     hal::Error validate(uint32_t* outNumTypes, uint32_t* outNumRequests) override;
     hal::Error presentOrValidate(uint32_t* outNumTypes, uint32_t* outNumRequests,
@@ -317,13 +315,13 @@
     virtual bool isVsyncPeriodSwitchSupported() const override;
 
 private:
-    int32_t getAttribute(hal::HWConfigId configId, hal::Attribute attribute);
-    void loadConfig(hal::HWConfigId configId);
+    int32_t getAttribute(hal::HWConfigId, hal::Attribute);
+    void loadConfig(hal::HWConfigId);
     void loadConfigs();
 
     // This may fail (and return a null pointer) if no layer with this ID exists
     // on this display
-    Layer* getLayerById(hal::HWLayerId id) const;
+    Layer* getLayerById(hal::HWLayerId) const;
 
     friend android::TestableSurfaceFlinger;
 
diff --git a/services/surfaceflinger/DisplayHardware/HWComposer.cpp b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
index 195182a..2379e6e 100644
--- a/services/surfaceflinger/DisplayHardware/HWComposer.cpp
+++ b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
@@ -186,7 +186,7 @@
     return mCapabilities.count(capability) > 0;
 }
 
-bool HWComposer::hasDisplayCapability(DisplayId displayId,
+bool HWComposer::hasDisplayCapability(HalDisplayId displayId,
                                       hal::DisplayCapability capability) const {
     RETURN_IF_INVALID_DISPLAY(displayId, false);
     return mDisplayData.at(displayId).hwcDisplay->getCapabilities().count(capability) > 0;
@@ -214,10 +214,8 @@
     RETURN_IF_INVALID_DISPLAY(*displayId, false);
 
     auto& displayData = mDisplayData[*displayId];
-    if (displayData.isVirtual) {
-        LOG_DISPLAY_ERROR(*displayId, "Invalid operation on virtual display");
-        return false;
-    }
+    LOG_FATAL_IF(displayData.isVirtual, "%s: Invalid operation on virtual display with ID %s",
+                 __FUNCTION__, to_string(*displayId));
 
     {
         std::lock_guard lock(displayData.lastHwVsyncLock);
@@ -244,11 +242,6 @@
 
 std::optional<DisplayId> HWComposer::allocateVirtualDisplay(uint32_t width, uint32_t height,
                                                             ui::PixelFormat* format) {
-    if (mRemainingHwcVirtualDisplays == 0) {
-        ALOGE("%s: No remaining virtual displays", __FUNCTION__);
-        return {};
-    }
-
     if (SurfaceFlinger::maxVirtualDisplaySize != 0 &&
         (width > SurfaceFlinger::maxVirtualDisplaySize ||
          height > SurfaceFlinger::maxVirtualDisplaySize)) {
@@ -256,31 +249,28 @@
               height, SurfaceFlinger::maxVirtualDisplaySize);
         return {};
     }
+
+    const auto displayId = mVirtualIdGenerator.nextId();
+    if (!displayId) {
+        ALOGE("%s: No remaining virtual displays", __FUNCTION__);
+        return {};
+    }
+
     hal::HWDisplayId hwcDisplayId = 0;
     const auto error = static_cast<hal::Error>(
             mComposer->createVirtualDisplay(width, height, format, &hwcDisplayId));
     if (error != hal::Error::NONE) {
         ALOGE("%s: Failed to create HWC virtual display", __FUNCTION__);
+        mVirtualIdGenerator.markUnused(*displayId);
         return {};
     }
 
     auto display = std::make_unique<HWC2::impl::Display>(*mComposer.get(), mCapabilities,
                                                          hwcDisplayId, hal::DisplayType::VIRTUAL);
     display->setConnected(true);
-
-    DisplayId displayId;
-    if (mFreeVirtualDisplayIds.empty()) {
-        displayId = getVirtualDisplayId(mNextVirtualDisplayId++);
-    } else {
-        displayId = *mFreeVirtualDisplayIds.begin();
-        mFreeVirtualDisplayIds.erase(displayId);
-    }
-
-    auto& displayData = mDisplayData[displayId];
+    auto& displayData = mDisplayData[*displayId];
     displayData.hwcDisplay = std::move(display);
     displayData.isVirtual = true;
-
-    --mRemainingHwcVirtualDisplays;
     return displayId;
 }
 
@@ -301,7 +291,7 @@
     mPhysicalDisplayIdMap[hwcDisplayId] = displayId;
 }
 
-HWC2::Layer* HWComposer::createLayer(DisplayId displayId) {
+HWC2::Layer* HWComposer::createLayer(HalDisplayId displayId) {
     RETURN_IF_INVALID_DISPLAY(displayId, nullptr);
 
     HWC2::Layer* layer;
@@ -310,14 +300,14 @@
     return layer;
 }
 
-void HWComposer::destroyLayer(DisplayId displayId, HWC2::Layer* layer) {
+void HWComposer::destroyLayer(HalDisplayId displayId, HWC2::Layer* layer) {
     RETURN_IF_INVALID_DISPLAY(displayId);
 
     auto error = mDisplayData[displayId].hwcDisplay->destroyLayer(layer);
     RETURN_IF_HWC_ERROR(error, displayId);
 }
 
-nsecs_t HWComposer::getRefreshTimestamp(DisplayId displayId) const {
+nsecs_t HWComposer::getRefreshTimestamp(PhysicalDisplayId displayId) const {
     RETURN_IF_INVALID_DISPLAY(displayId, 0);
     const auto& displayData = mDisplayData.at(displayId);
     // this returns the last refresh timestamp.
@@ -329,13 +319,13 @@
     return now - ((now - displayData.lastHwVsync) % vsyncPeriodNanos);
 }
 
-bool HWComposer::isConnected(DisplayId displayId) const {
+bool HWComposer::isConnected(PhysicalDisplayId displayId) const {
     RETURN_IF_INVALID_DISPLAY(displayId, false);
     return mDisplayData.at(displayId).hwcDisplay->isConnected();
 }
 
 std::vector<std::shared_ptr<const HWC2::Display::Config>> HWComposer::getConfigs(
-        DisplayId displayId) const {
+        PhysicalDisplayId displayId) const {
     RETURN_IF_INVALID_DISPLAY(displayId, {});
 
     const auto& displayData = mDisplayData.at(displayId);
@@ -349,7 +339,7 @@
 }
 
 std::shared_ptr<const HWC2::Display::Config> HWComposer::getActiveConfig(
-        DisplayId displayId) const {
+        PhysicalDisplayId displayId) const {
     RETURN_IF_INVALID_DISPLAY(displayId, nullptr);
 
     std::shared_ptr<const HWC2::Display::Config> config;
@@ -371,7 +361,7 @@
 
 // Composer 2.4
 
-DisplayConnectionType HWComposer::getDisplayConnectionType(DisplayId displayId) const {
+DisplayConnectionType HWComposer::getDisplayConnectionType(PhysicalDisplayId displayId) const {
     RETURN_IF_INVALID_DISPLAY(displayId, DisplayConnectionType::Internal);
     const auto& hwcDisplay = mDisplayData.at(displayId).hwcDisplay;
 
@@ -386,12 +376,12 @@
     return type;
 }
 
-bool HWComposer::isVsyncPeriodSwitchSupported(DisplayId displayId) const {
+bool HWComposer::isVsyncPeriodSwitchSupported(PhysicalDisplayId displayId) const {
     RETURN_IF_INVALID_DISPLAY(displayId, false);
     return mDisplayData.at(displayId).hwcDisplay->isVsyncPeriodSwitchSupported();
 }
 
-nsecs_t HWComposer::getDisplayVsyncPeriod(DisplayId displayId) const {
+nsecs_t HWComposer::getDisplayVsyncPeriod(PhysicalDisplayId displayId) const {
     RETURN_IF_INVALID_DISPLAY(displayId, 0);
 
     nsecs_t vsyncPeriodNanos;
@@ -400,7 +390,7 @@
     return vsyncPeriodNanos;
 }
 
-int HWComposer::getActiveConfigIndex(DisplayId displayId) const {
+int HWComposer::getActiveConfigIndex(PhysicalDisplayId displayId) const {
     RETURN_IF_INVALID_DISPLAY(displayId, -1);
 
     int index;
@@ -420,7 +410,7 @@
     return index;
 }
 
-std::vector<ui::ColorMode> HWComposer::getColorModes(DisplayId displayId) const {
+std::vector<ui::ColorMode> HWComposer::getColorModes(PhysicalDisplayId displayId) const {
     RETURN_IF_INVALID_DISPLAY(displayId, {});
 
     std::vector<ui::ColorMode> modes;
@@ -429,7 +419,7 @@
     return modes;
 }
 
-status_t HWComposer::setActiveColorMode(DisplayId displayId, ui::ColorMode mode,
+status_t HWComposer::setActiveColorMode(PhysicalDisplayId displayId, ui::ColorMode mode,
                                         ui::RenderIntent renderIntent) {
     RETURN_IF_INVALID_DISPLAY(displayId, BAD_INDEX);
 
@@ -443,14 +433,12 @@
     return NO_ERROR;
 }
 
-void HWComposer::setVsyncEnabled(DisplayId displayId, hal::Vsync enabled) {
+void HWComposer::setVsyncEnabled(PhysicalDisplayId displayId, hal::Vsync enabled) {
     RETURN_IF_INVALID_DISPLAY(displayId);
     auto& displayData = mDisplayData[displayId];
 
-    if (displayData.isVirtual) {
-        LOG_DISPLAY_ERROR(displayId, "Invalid operation on virtual display");
-        return;
-    }
+    LOG_FATAL_IF(displayData.isVirtual, "%s: Invalid operation on virtual display with ID %s",
+                 __FUNCTION__, to_string(*displayId));
 
     // NOTE: we use our own internal lock here because we have to call
     // into the HWC with the lock held, and we want to make sure
@@ -471,7 +459,7 @@
     ATRACE_INT(tag.c_str(), enabled == hal::Vsync::ENABLE ? 1 : 0);
 }
 
-status_t HWComposer::setClientTarget(DisplayId displayId, uint32_t slot,
+status_t HWComposer::setClientTarget(HalDisplayId displayId, uint32_t slot,
                                      const sp<Fence>& acquireFence, const sp<GraphicBuffer>& target,
                                      ui::Dataspace dataspace) {
     RETURN_IF_INVALID_DISPLAY(displayId, BAD_INDEX);
@@ -484,7 +472,7 @@
 }
 
 status_t HWComposer::getDeviceCompositionChanges(
-        DisplayId displayId, bool frameUsesClientComposition,
+        HalDisplayId displayId, bool frameUsesClientComposition,
         std::optional<android::HWComposer::DeviceRequestedChanges>* outChanges) {
     ATRACE_CALL();
 
@@ -554,12 +542,12 @@
     return NO_ERROR;
 }
 
-sp<Fence> HWComposer::getPresentFence(DisplayId displayId) const {
+sp<Fence> HWComposer::getPresentFence(HalDisplayId displayId) const {
     RETURN_IF_INVALID_DISPLAY(displayId, Fence::NO_FENCE);
     return mDisplayData.at(displayId).lastPresentFence;
 }
 
-sp<Fence> HWComposer::getLayerReleaseFence(DisplayId displayId, HWC2::Layer* layer) const {
+sp<Fence> HWComposer::getLayerReleaseFence(HalDisplayId displayId, HWC2::Layer* layer) const {
     RETURN_IF_INVALID_DISPLAY(displayId, Fence::NO_FENCE);
     const auto& displayFences = mDisplayData.at(displayId).releaseFences;
     auto fence = displayFences.find(layer);
@@ -570,7 +558,7 @@
     return fence->second;
 }
 
-status_t HWComposer::presentAndGetReleaseFences(DisplayId displayId) {
+status_t HWComposer::presentAndGetReleaseFences(HalDisplayId displayId) {
     ATRACE_CALL();
 
     RETURN_IF_INVALID_DISPLAY(displayId, BAD_INDEX);
@@ -598,14 +586,12 @@
     return NO_ERROR;
 }
 
-status_t HWComposer::setPowerMode(DisplayId displayId, hal::PowerMode mode) {
+status_t HWComposer::setPowerMode(PhysicalDisplayId displayId, hal::PowerMode mode) {
     RETURN_IF_INVALID_DISPLAY(displayId, BAD_INDEX);
 
     const auto& displayData = mDisplayData[displayId];
-    if (displayData.isVirtual) {
-        LOG_DISPLAY_ERROR(displayId, "Invalid operation on virtual display");
-        return INVALID_OPERATION;
-    }
+    LOG_FATAL_IF(displayData.isVirtual, "%s: Invalid operation on virtual display with ID %s",
+                 __FUNCTION__, to_string(*displayId));
 
     if (mode == hal::PowerMode::OFF) {
         setVsyncEnabled(displayId, hal::Vsync::DISABLE);
@@ -654,7 +640,8 @@
 }
 
 status_t HWComposer::setActiveConfigWithConstraints(
-        DisplayId displayId, size_t configId, const hal::VsyncPeriodChangeConstraints& constraints,
+        PhysicalDisplayId displayId, size_t configId,
+        const hal::VsyncPeriodChangeConstraints& constraints,
         hal::VsyncPeriodChangeTimeline* outTimeline) {
     RETURN_IF_INVALID_DISPLAY(displayId, BAD_INDEX);
 
@@ -671,7 +658,7 @@
     return NO_ERROR;
 }
 
-status_t HWComposer::setColorTransform(DisplayId displayId, const mat4& transform) {
+status_t HWComposer::setColorTransform(HalDisplayId displayId, const mat4& transform) {
     RETURN_IF_INVALID_DISPLAY(displayId, BAD_INDEX);
 
     auto& displayData = mDisplayData[displayId];
@@ -684,15 +671,14 @@
     return NO_ERROR;
 }
 
-void HWComposer::disconnectDisplay(DisplayId displayId) {
+void HWComposer::disconnectDisplay(HalDisplayId displayId) {
     RETURN_IF_INVALID_DISPLAY(displayId);
     auto& displayData = mDisplayData[displayId];
 
     // If this was a virtual display, add its slot back for reuse by future
     // virtual displays
     if (displayData.isVirtual) {
-        mFreeVirtualDisplayIds.insert(displayId);
-        ++mRemainingHwcVirtualDisplays;
+        mVirtualIdGenerator.markUnused(*HalVirtualDisplayId::tryCast(displayId));
     }
 
     const auto hwcDisplayId = displayData.hwcDisplay->getId();
@@ -707,27 +693,25 @@
     mDisplayData.erase(displayId);
 }
 
-status_t HWComposer::setOutputBuffer(DisplayId displayId, const sp<Fence>& acquireFence,
+status_t HWComposer::setOutputBuffer(HalVirtualDisplayId displayId, const sp<Fence>& acquireFence,
                                      const sp<GraphicBuffer>& buffer) {
     RETURN_IF_INVALID_DISPLAY(displayId, BAD_INDEX);
     const auto& displayData = mDisplayData[displayId];
 
-    if (!displayData.isVirtual) {
-        LOG_DISPLAY_ERROR(displayId, "Invalid operation on physical display");
-        return INVALID_OPERATION;
-    }
+    LOG_FATAL_IF(!displayData.isVirtual, "%s: Invalid operation on physical display with ID %s",
+                 __FUNCTION__, to_string(*displayId));
 
     auto error = displayData.hwcDisplay->setOutputBuffer(buffer, acquireFence);
     RETURN_IF_HWC_ERROR(error, displayId, UNKNOWN_ERROR);
     return NO_ERROR;
 }
 
-void HWComposer::clearReleaseFences(DisplayId displayId) {
+void HWComposer::clearReleaseFences(HalDisplayId displayId) {
     RETURN_IF_INVALID_DISPLAY(displayId);
     mDisplayData[displayId].releaseFences.clear();
 }
 
-status_t HWComposer::getHdrCapabilities(DisplayId displayId, HdrCapabilities* outCapabilities) {
+status_t HWComposer::getHdrCapabilities(HalDisplayId displayId, HdrCapabilities* outCapabilities) {
     RETURN_IF_INVALID_DISPLAY(displayId, BAD_INDEX);
 
     auto& hwcDisplay = mDisplayData[displayId].hwcDisplay;
@@ -736,12 +720,12 @@
     return NO_ERROR;
 }
 
-int32_t HWComposer::getSupportedPerFrameMetadata(DisplayId displayId) const {
+int32_t HWComposer::getSupportedPerFrameMetadata(HalDisplayId displayId) const {
     RETURN_IF_INVALID_DISPLAY(displayId, 0);
     return mDisplayData.at(displayId).hwcDisplay->getSupportedPerFrameMetadata();
 }
 
-std::vector<ui::RenderIntent> HWComposer::getRenderIntents(DisplayId displayId,
+std::vector<ui::RenderIntent> HWComposer::getRenderIntents(HalDisplayId displayId,
                                                            ui::ColorMode colorMode) const {
     RETURN_IF_INVALID_DISPLAY(displayId, {});
 
@@ -751,7 +735,7 @@
     return renderIntents;
 }
 
-mat4 HWComposer::getDataspaceSaturationMatrix(DisplayId displayId, ui::Dataspace dataspace) {
+mat4 HWComposer::getDataspaceSaturationMatrix(HalDisplayId displayId, ui::Dataspace dataspace) {
     RETURN_IF_INVALID_DISPLAY(displayId, {});
 
     mat4 matrix;
@@ -761,7 +745,7 @@
     return matrix;
 }
 
-status_t HWComposer::getDisplayedContentSamplingAttributes(DisplayId displayId,
+status_t HWComposer::getDisplayedContentSamplingAttributes(HalDisplayId displayId,
                                                            ui::PixelFormat* outFormat,
                                                            ui::Dataspace* outDataspace,
                                                            uint8_t* outComponentMask) {
@@ -775,7 +759,7 @@
     return NO_ERROR;
 }
 
-status_t HWComposer::setDisplayContentSamplingEnabled(DisplayId displayId, bool enabled,
+status_t HWComposer::setDisplayContentSamplingEnabled(HalDisplayId displayId, bool enabled,
                                                       uint8_t componentMask, uint64_t maxFrames) {
     RETURN_IF_INVALID_DISPLAY(displayId, BAD_INDEX);
     const auto error =
@@ -789,7 +773,7 @@
     return NO_ERROR;
 }
 
-status_t HWComposer::getDisplayedContentSample(DisplayId displayId, uint64_t maxFrames,
+status_t HWComposer::getDisplayedContentSample(HalDisplayId displayId, uint64_t maxFrames,
                                                uint64_t timestamp, DisplayedFrameStats* outStats) {
     RETURN_IF_INVALID_DISPLAY(displayId, BAD_INDEX);
     const auto error =
@@ -799,7 +783,8 @@
     return NO_ERROR;
 }
 
-std::future<status_t> HWComposer::setDisplayBrightness(DisplayId displayId, float brightness) {
+std::future<status_t> HWComposer::setDisplayBrightness(PhysicalDisplayId displayId,
+                                                       float brightness) {
     RETURN_IF_INVALID_DISPLAY(displayId, promise::yield<status_t>(BAD_INDEX));
     auto& display = mDisplayData[displayId].hwcDisplay;
 
@@ -816,7 +801,7 @@
             });
 }
 
-status_t HWComposer::setAutoLowLatencyMode(DisplayId displayId, bool on) {
+status_t HWComposer::setAutoLowLatencyMode(PhysicalDisplayId displayId, bool on) {
     RETURN_IF_INVALID_DISPLAY(displayId, BAD_INDEX);
     const auto error = mDisplayData[displayId].hwcDisplay->setAutoLowLatencyMode(on);
     if (error == hal::Error::UNSUPPORTED) {
@@ -830,7 +815,7 @@
 }
 
 status_t HWComposer::getSupportedContentTypes(
-        DisplayId displayId, std::vector<hal::ContentType>* outSupportedContentTypes) {
+        PhysicalDisplayId displayId, std::vector<hal::ContentType>* outSupportedContentTypes) {
     RETURN_IF_INVALID_DISPLAY(displayId, BAD_INDEX);
     const auto error =
             mDisplayData[displayId].hwcDisplay->getSupportedContentTypes(outSupportedContentTypes);
@@ -840,7 +825,7 @@
     return NO_ERROR;
 }
 
-status_t HWComposer::setContentType(DisplayId displayId, hal::ContentType contentType) {
+status_t HWComposer::setContentType(PhysicalDisplayId displayId, hal::ContentType contentType) {
     RETURN_IF_INVALID_DISPLAY(displayId, BAD_INDEX);
     const auto error = mDisplayData[displayId].hwcDisplay->setContentType(contentType);
     if (error == hal::Error::UNSUPPORTED) {
diff --git a/services/surfaceflinger/DisplayHardware/HWComposer.h b/services/surfaceflinger/DisplayHardware/HWComposer.h
index 488cdc5..028a9a4 100644
--- a/services/surfaceflinger/DisplayHardware/HWComposer.h
+++ b/services/surfaceflinger/DisplayHardware/HWComposer.h
@@ -38,6 +38,7 @@
 #include <utils/StrongPointer.h>
 #include <utils/Timers.h>
 
+#include "DisplayIdGenerator.h"
 #include "DisplayIdentification.h"
 #include "HWC2.h"
 #include "Hal.h"
@@ -88,7 +89,7 @@
                                               DisplayIdentificationData* outData) const = 0;
 
     virtual bool hasCapability(hal::Capability) const = 0;
-    virtual bool hasDisplayCapability(DisplayId, hal::DisplayCapability) const = 0;
+    virtual bool hasDisplayCapability(HalDisplayId, hal::DisplayCapability) const = 0;
 
     // Attempts to allocate a virtual display and returns its ID if created on the HWC device.
     virtual std::optional<DisplayId> allocateVirtualDisplay(uint32_t width, uint32_t height,
@@ -97,9 +98,9 @@
     virtual void allocatePhysicalDisplay(hal::HWDisplayId, PhysicalDisplayId) = 0;
 
     // Attempts to create a new layer on this display
-    virtual HWC2::Layer* createLayer(DisplayId) = 0;
+    virtual HWC2::Layer* createLayer(HalDisplayId) = 0;
     // Destroy a previously created layer
-    virtual void destroyLayer(DisplayId, HWC2::Layer*) = 0;
+    virtual void destroyLayer(HalDisplayId, HWC2::Layer*) = 0;
 
     // Gets any required composition change requests from the HWC device.
     //
@@ -109,61 +110,60 @@
     // with fewer handshakes, but this does not work if client composition is
     // expected.
     virtual status_t getDeviceCompositionChanges(
-            DisplayId, bool frameUsesClientComposition,
+            HalDisplayId, bool frameUsesClientComposition,
             std::optional<DeviceRequestedChanges>* outChanges) = 0;
 
-    virtual status_t setClientTarget(DisplayId, uint32_t slot, const sp<Fence>& acquireFence,
+    virtual status_t setClientTarget(HalDisplayId, uint32_t slot, const sp<Fence>& acquireFence,
                                      const sp<GraphicBuffer>& target, ui::Dataspace) = 0;
 
     // Present layers to the display and read releaseFences.
-    virtual status_t presentAndGetReleaseFences(DisplayId) = 0;
+    virtual status_t presentAndGetReleaseFences(HalDisplayId) = 0;
 
     // set power mode
-    virtual status_t setPowerMode(DisplayId, hal::PowerMode) = 0;
+    virtual status_t setPowerMode(PhysicalDisplayId, hal::PowerMode) = 0;
 
     // Sets a color transform to be applied to the result of composition
-    virtual status_t setColorTransform(DisplayId, const mat4& transform) = 0;
+    virtual status_t setColorTransform(HalDisplayId, const mat4& transform) = 0;
 
-    // reset state when an external, non-virtual display is disconnected
-    virtual void disconnectDisplay(DisplayId) = 0;
+    // reset state when a display is disconnected
+    virtual void disconnectDisplay(HalDisplayId) = 0;
 
     // get the present fence received from the last call to present.
-    virtual sp<Fence> getPresentFence(DisplayId) const = 0;
+    virtual sp<Fence> getPresentFence(HalDisplayId) const = 0;
 
     // Get last release fence for the given layer
-    virtual sp<Fence> getLayerReleaseFence(DisplayId, HWC2::Layer*) const = 0;
+    virtual sp<Fence> getLayerReleaseFence(HalDisplayId, HWC2::Layer*) const = 0;
 
     // Set the output buffer and acquire fence for a virtual display.
-    // Returns INVALID_OPERATION if displayId is not a virtual display.
-    virtual status_t setOutputBuffer(DisplayId, const sp<Fence>& acquireFence,
+    virtual status_t setOutputBuffer(HalVirtualDisplayId, const sp<Fence>& acquireFence,
                                      const sp<GraphicBuffer>& buffer) = 0;
 
     // After SurfaceFlinger has retrieved the release fences for all the frames,
     // it can call this to clear the shared pointers in the release fence map
-    virtual void clearReleaseFences(DisplayId) = 0;
+    virtual void clearReleaseFences(HalDisplayId) = 0;
 
     // Fetches the HDR capabilities of the given display
-    virtual status_t getHdrCapabilities(DisplayId, HdrCapabilities* outCapabilities) = 0;
+    virtual status_t getHdrCapabilities(HalDisplayId, HdrCapabilities* outCapabilities) = 0;
 
-    virtual int32_t getSupportedPerFrameMetadata(DisplayId) const = 0;
+    virtual int32_t getSupportedPerFrameMetadata(HalDisplayId) const = 0;
 
     // Returns the available RenderIntent of the given display.
-    virtual std::vector<ui::RenderIntent> getRenderIntents(DisplayId, ui::ColorMode) const = 0;
+    virtual std::vector<ui::RenderIntent> getRenderIntents(HalDisplayId, ui::ColorMode) const = 0;
 
-    virtual mat4 getDataspaceSaturationMatrix(DisplayId, ui::Dataspace) = 0;
+    virtual mat4 getDataspaceSaturationMatrix(HalDisplayId, ui::Dataspace) = 0;
 
     // Returns the attributes of the color sampling engine.
-    virtual status_t getDisplayedContentSamplingAttributes(DisplayId, ui::PixelFormat* outFormat,
+    virtual status_t getDisplayedContentSamplingAttributes(HalDisplayId, ui::PixelFormat* outFormat,
                                                            ui::Dataspace* outDataspace,
                                                            uint8_t* outComponentMask) = 0;
-    virtual status_t setDisplayContentSamplingEnabled(DisplayId, bool enabled,
+    virtual status_t setDisplayContentSamplingEnabled(HalDisplayId, bool enabled,
                                                       uint8_t componentMask,
                                                       uint64_t maxFrames) = 0;
-    virtual status_t getDisplayedContentSample(DisplayId, uint64_t maxFrames, uint64_t timestamp,
+    virtual status_t getDisplayedContentSample(HalDisplayId, uint64_t maxFrames, uint64_t timestamp,
                                                DisplayedFrameStats* outStats) = 0;
 
     // Sets the brightness of a display.
-    virtual std::future<status_t> setDisplayBrightness(DisplayId, float brightness) = 0;
+    virtual std::future<status_t> setDisplayBrightness(PhysicalDisplayId, float brightness) = 0;
 
     // Events handling ---------------------------------------------------------
 
@@ -174,33 +174,35 @@
                                                                hal::Connection) = 0;
 
     virtual bool onVsync(hal::HWDisplayId, int64_t timestamp) = 0;
-    virtual void setVsyncEnabled(DisplayId, hal::Vsync enabled) = 0;
+    virtual void setVsyncEnabled(PhysicalDisplayId, hal::Vsync enabled) = 0;
 
-    virtual nsecs_t getRefreshTimestamp(DisplayId) const = 0;
-    virtual bool isConnected(DisplayId) const = 0;
+    virtual nsecs_t getRefreshTimestamp(PhysicalDisplayId) const = 0;
+    virtual bool isConnected(PhysicalDisplayId) const = 0;
 
     // Non-const because it can update configMap inside of mDisplayData
     virtual std::vector<std::shared_ptr<const HWC2::Display::Config>> getConfigs(
-            DisplayId) const = 0;
+            PhysicalDisplayId) const = 0;
 
-    virtual std::shared_ptr<const HWC2::Display::Config> getActiveConfig(DisplayId) const = 0;
-    virtual int getActiveConfigIndex(DisplayId) const = 0;
+    virtual std::shared_ptr<const HWC2::Display::Config> getActiveConfig(
+            PhysicalDisplayId) const = 0;
+    virtual int getActiveConfigIndex(PhysicalDisplayId) const = 0;
 
-    virtual std::vector<ui::ColorMode> getColorModes(DisplayId) const = 0;
+    virtual std::vector<ui::ColorMode> getColorModes(PhysicalDisplayId) const = 0;
 
-    virtual status_t setActiveColorMode(DisplayId, ui::ColorMode mode, ui::RenderIntent) = 0;
+    virtual status_t setActiveColorMode(PhysicalDisplayId, ui::ColorMode mode,
+                                        ui::RenderIntent) = 0;
 
     // Composer 2.4
-    virtual DisplayConnectionType getDisplayConnectionType(DisplayId) const = 0;
-    virtual bool isVsyncPeriodSwitchSupported(DisplayId) const = 0;
-    virtual nsecs_t getDisplayVsyncPeriod(DisplayId) const = 0;
+    virtual DisplayConnectionType getDisplayConnectionType(PhysicalDisplayId) const = 0;
+    virtual bool isVsyncPeriodSwitchSupported(PhysicalDisplayId) const = 0;
+    virtual nsecs_t getDisplayVsyncPeriod(PhysicalDisplayId) const = 0;
     virtual status_t setActiveConfigWithConstraints(
-            DisplayId, size_t configId, const hal::VsyncPeriodChangeConstraints&,
+            PhysicalDisplayId, size_t configId, const hal::VsyncPeriodChangeConstraints&,
             hal::VsyncPeriodChangeTimeline* outTimeline) = 0;
-    virtual status_t setAutoLowLatencyMode(DisplayId, bool on) = 0;
+    virtual status_t setAutoLowLatencyMode(PhysicalDisplayId, bool on) = 0;
     virtual status_t getSupportedContentTypes(
-            DisplayId, std::vector<hal::ContentType>* outSupportedContentTypes) = 0;
-    virtual status_t setContentType(DisplayId, hal::ContentType) = 0;
+            PhysicalDisplayId, std::vector<hal::ContentType>* outSupportedContentTypes) = 0;
+    virtual status_t setContentType(PhysicalDisplayId, hal::ContentType) = 0;
     virtual const std::unordered_map<std::string, bool>& getSupportedLayerGenericMetadata()
             const = 0;
 
@@ -232,7 +234,7 @@
                                       DisplayIdentificationData* outData) const override;
 
     bool hasCapability(hal::Capability) const override;
-    bool hasDisplayCapability(DisplayId, hal::DisplayCapability) const override;
+    bool hasDisplayCapability(HalDisplayId, hal::DisplayCapability) const override;
 
     // Attempts to allocate a virtual display and returns its ID if created on the HWC device.
     std::optional<DisplayId> allocateVirtualDisplay(uint32_t width, uint32_t height,
@@ -242,63 +244,62 @@
     void allocatePhysicalDisplay(hal::HWDisplayId, PhysicalDisplayId) override;
 
     // Attempts to create a new layer on this display
-    HWC2::Layer* createLayer(DisplayId) override;
+    HWC2::Layer* createLayer(HalDisplayId) override;
     // Destroy a previously created layer
-    void destroyLayer(DisplayId, HWC2::Layer*) override;
+    void destroyLayer(HalDisplayId, HWC2::Layer*) override;
 
     status_t getDeviceCompositionChanges(
-            DisplayId, bool frameUsesClientComposition,
+            HalDisplayId, bool frameUsesClientComposition,
             std::optional<DeviceRequestedChanges>* outChanges) override;
 
-    status_t setClientTarget(DisplayId, uint32_t slot, const sp<Fence>& acquireFence,
+    status_t setClientTarget(HalDisplayId, uint32_t slot, const sp<Fence>& acquireFence,
                              const sp<GraphicBuffer>& target, ui::Dataspace) override;
 
     // Present layers to the display and read releaseFences.
-    status_t presentAndGetReleaseFences(DisplayId) override;
+    status_t presentAndGetReleaseFences(HalDisplayId) override;
 
     // set power mode
-    status_t setPowerMode(DisplayId, hal::PowerMode mode) override;
+    status_t setPowerMode(PhysicalDisplayId, hal::PowerMode mode) override;
 
     // Sets a color transform to be applied to the result of composition
-    status_t setColorTransform(DisplayId, const mat4& transform) override;
+    status_t setColorTransform(HalDisplayId, const mat4& transform) override;
 
-    // reset state when an external, non-virtual display is disconnected
-    void disconnectDisplay(DisplayId) override;
+    // reset state when a display is disconnected
+    void disconnectDisplay(HalDisplayId) override;
 
     // get the present fence received from the last call to present.
-    sp<Fence> getPresentFence(DisplayId) const override;
+    sp<Fence> getPresentFence(HalDisplayId) const override;
 
     // Get last release fence for the given layer
-    sp<Fence> getLayerReleaseFence(DisplayId, HWC2::Layer*) const override;
+    sp<Fence> getLayerReleaseFence(HalDisplayId, HWC2::Layer*) const override;
 
     // Set the output buffer and acquire fence for a virtual display.
-    // Returns INVALID_OPERATION if displayId is not a virtual display.
-    status_t setOutputBuffer(DisplayId, const sp<Fence>& acquireFence,
+    status_t setOutputBuffer(HalVirtualDisplayId, const sp<Fence>& acquireFence,
                              const sp<GraphicBuffer>& buffer) override;
 
     // After SurfaceFlinger has retrieved the release fences for all the frames,
     // it can call this to clear the shared pointers in the release fence map
-    void clearReleaseFences(DisplayId) override;
+    void clearReleaseFences(HalDisplayId) override;
 
     // Fetches the HDR capabilities of the given display
-    status_t getHdrCapabilities(DisplayId, HdrCapabilities* outCapabilities) override;
+    status_t getHdrCapabilities(HalDisplayId, HdrCapabilities* outCapabilities) override;
 
-    int32_t getSupportedPerFrameMetadata(DisplayId) const override;
+    int32_t getSupportedPerFrameMetadata(HalDisplayId) const override;
 
     // Returns the available RenderIntent of the given display.
-    std::vector<ui::RenderIntent> getRenderIntents(DisplayId, ui::ColorMode) const override;
+    std::vector<ui::RenderIntent> getRenderIntents(HalDisplayId, ui::ColorMode) const override;
 
-    mat4 getDataspaceSaturationMatrix(DisplayId, ui::Dataspace) override;
+    mat4 getDataspaceSaturationMatrix(HalDisplayId, ui::Dataspace) override;
 
     // Returns the attributes of the color sampling engine.
-    status_t getDisplayedContentSamplingAttributes(DisplayId, ui::PixelFormat* outFormat,
+    status_t getDisplayedContentSamplingAttributes(HalDisplayId, ui::PixelFormat* outFormat,
                                                    ui::Dataspace* outDataspace,
                                                    uint8_t* outComponentMask) override;
-    status_t setDisplayContentSamplingEnabled(DisplayId, bool enabled, uint8_t componentMask,
+    status_t setDisplayContentSamplingEnabled(HalDisplayId, bool enabled, uint8_t componentMask,
                                               uint64_t maxFrames) override;
-    status_t getDisplayedContentSample(DisplayId, uint64_t maxFrames, uint64_t timestamp,
+    status_t getDisplayedContentSample(HalDisplayId, uint64_t maxFrames, uint64_t timestamp,
                                        DisplayedFrameStats* outStats) override;
-    std::future<status_t> setDisplayBrightness(DisplayId, float brightness) override;
+    std::future<status_t> setDisplayBrightness(PhysicalDisplayId, float brightness) override;
 
     // Events handling ---------------------------------------------------------
 
@@ -307,31 +308,32 @@
     std::optional<DisplayIdentificationInfo> onHotplug(hal::HWDisplayId, hal::Connection) override;
 
     bool onVsync(hal::HWDisplayId, int64_t timestamp) override;
-    void setVsyncEnabled(DisplayId, hal::Vsync enabled) override;
+    void setVsyncEnabled(PhysicalDisplayId, hal::Vsync enabled) override;
 
-    nsecs_t getRefreshTimestamp(DisplayId) const override;
-    bool isConnected(DisplayId) const override;
+    nsecs_t getRefreshTimestamp(PhysicalDisplayId) const override;
+    bool isConnected(PhysicalDisplayId) const override;
 
     // Non-const because it can update configMap inside of mDisplayData
-    std::vector<std::shared_ptr<const HWC2::Display::Config>> getConfigs(DisplayId) const override;
+    std::vector<std::shared_ptr<const HWC2::Display::Config>> getConfigs(
+            PhysicalDisplayId) const override;
 
-    std::shared_ptr<const HWC2::Display::Config> getActiveConfig(DisplayId) const override;
-    int getActiveConfigIndex(DisplayId) const override;
+    std::shared_ptr<const HWC2::Display::Config> getActiveConfig(PhysicalDisplayId) const override;
+    int getActiveConfigIndex(PhysicalDisplayId) const override;
 
-    std::vector<ui::ColorMode> getColorModes(DisplayId) const override;
+    std::vector<ui::ColorMode> getColorModes(PhysicalDisplayId) const override;
 
-    status_t setActiveColorMode(DisplayId, ui::ColorMode, ui::RenderIntent) override;
+    status_t setActiveColorMode(PhysicalDisplayId, ui::ColorMode, ui::RenderIntent) override;
 
     // Composer 2.4
-    DisplayConnectionType getDisplayConnectionType(DisplayId) const override;
-    bool isVsyncPeriodSwitchSupported(DisplayId) const override;
-    nsecs_t getDisplayVsyncPeriod(DisplayId) const override;
-    status_t setActiveConfigWithConstraints(DisplayId, size_t configId,
+    DisplayConnectionType getDisplayConnectionType(PhysicalDisplayId) const override;
+    bool isVsyncPeriodSwitchSupported(PhysicalDisplayId) const override;
+    nsecs_t getDisplayVsyncPeriod(PhysicalDisplayId) const override;
+    status_t setActiveConfigWithConstraints(PhysicalDisplayId, size_t configId,
                                             const hal::VsyncPeriodChangeConstraints&,
                                             hal::VsyncPeriodChangeTimeline* outTimeline) override;
-    status_t setAutoLowLatencyMode(DisplayId, bool) override;
-    status_t getSupportedContentTypes(DisplayId, std::vector<hal::ContentType>*) override;
-    status_t setContentType(DisplayId, hal::ContentType) override;
+    status_t setAutoLowLatencyMode(PhysicalDisplayId, bool) override;
+    status_t getSupportedContentTypes(PhysicalDisplayId, std::vector<hal::ContentType>*) override;
+    status_t setContentType(PhysicalDisplayId, hal::ContentType) override;
 
     const std::unordered_map<std::string, bool>& getSupportedLayerGenericMetadata() const override;
 
@@ -385,7 +387,7 @@
         nsecs_t lastHwVsync GUARDED_BY(lastHwVsyncLock) = 0;
     };
 
-    std::unordered_map<DisplayId, DisplayData> mDisplayData;
+    std::unordered_map<HalDisplayId, DisplayData> mDisplayData;
 
     std::unique_ptr<android::Hwc2::Composer> mComposer;
     std::unordered_set<hal::Capability> mCapabilities;
@@ -397,9 +399,7 @@
     std::optional<hal::HWDisplayId> mExternalHwcDisplayId;
     bool mHasMultiDisplaySupport = false;
 
-    std::unordered_set<DisplayId> mFreeVirtualDisplayIds;
-    uint32_t mNextVirtualDisplayId = 0;
-    uint32_t mRemainingHwcVirtualDisplays{getMaxVirtualDisplayCount()};
+    RandomDisplayIdGenerator<HalVirtualDisplayId> mVirtualIdGenerator{getMaxVirtualDisplayCount()};
 };
 
 } // namespace impl
diff --git a/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.cpp b/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.cpp
index fba3261..247ee23 100644
--- a/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.cpp
+++ b/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.cpp
@@ -57,8 +57,7 @@
     }
 }
 
-VirtualDisplaySurface::VirtualDisplaySurface(HWComposer& hwc,
-                                             const std::optional<DisplayId>& displayId,
+VirtualDisplaySurface::VirtualDisplaySurface(HWComposer& hwc, VirtualDisplayId displayId,
                                              const sp<IGraphicBufferProducer>& sink,
                                              const sp<IGraphicBufferProducer>& bqProducer,
                                              const sp<IGraphicBufferConsumer>& bqConsumer,
@@ -125,7 +124,7 @@
 }
 
 status_t VirtualDisplaySurface::beginFrame(bool mustRecompose) {
-    if (!mDisplayId) {
+    if (GpuVirtualDisplayId::tryCast(mDisplayId)) {
         return NO_ERROR;
     }
 
@@ -139,7 +138,7 @@
 }
 
 status_t VirtualDisplaySurface::prepareFrame(CompositionType compositionType) {
-    if (!mDisplayId) {
+    if (GpuVirtualDisplayId::tryCast(mDisplayId)) {
         return NO_ERROR;
     }
 
@@ -187,7 +186,7 @@
 }
 
 status_t VirtualDisplaySurface::advanceFrame() {
-    if (!mDisplayId) {
+    if (GpuVirtualDisplayId::tryCast(mDisplayId)) {
         return NO_ERROR;
     }
 
@@ -219,9 +218,11 @@
             mFbProducerSlot, fbBuffer.get(),
             mOutputProducerSlot, outBuffer.get());
 
+    const auto halDisplayId = HalVirtualDisplayId::tryCast(mDisplayId);
+    LOG_FATAL_IF(!halDisplayId);
     // At this point we know the output buffer acquire fence,
     // so update HWC state with it.
-    mHwc.setOutputBuffer(*mDisplayId, mOutputFence, outBuffer);
+    mHwc.setOutputBuffer(*halDisplayId, mOutputFence, outBuffer);
 
     status_t result = NO_ERROR;
     if (fbBuffer != nullptr) {
@@ -230,7 +231,7 @@
         mHwcBufferCache.getHwcBuffer(mFbProducerSlot, fbBuffer, &hwcSlot, &hwcBuffer);
 
         // TODO: Correctly propagate the dataspace from GL composition
-        result = mHwc.setClientTarget(*mDisplayId, hwcSlot, mFbFence, hwcBuffer,
+        result = mHwc.setClientTarget(*halDisplayId, hwcSlot, mFbFence, hwcBuffer,
                                       ui::Dataspace::UNKNOWN);
     }
 
@@ -238,7 +239,8 @@
 }
 
 void VirtualDisplaySurface::onFrameCommitted() {
-    if (!mDisplayId) {
+    const auto halDisplayId = HalVirtualDisplayId::tryCast(mDisplayId);
+    if (!halDisplayId) {
         return;
     }
 
@@ -246,7 +248,7 @@
             "Unexpected onFrameCommitted() in %s state", dbgStateStr());
     mDbgState = DBG_STATE_IDLE;
 
-    sp<Fence> retireFence = mHwc.getPresentFence(*mDisplayId);
+    sp<Fence> retireFence = mHwc.getPresentFence(*halDisplayId);
     if (mCompositionType == COMPOSITION_MIXED && mFbProducerSlot >= 0) {
         // release the scratch buffer back to the pool
         Mutex::Autolock lock(mMutex);
@@ -301,7 +303,7 @@
 
 status_t VirtualDisplaySurface::requestBuffer(int pslot,
         sp<GraphicBuffer>* outBuf) {
-    if (!mDisplayId) {
+    if (GpuVirtualDisplayId::tryCast(mDisplayId)) {
         return mSource[SOURCE_SINK]->requestBuffer(pslot, outBuf);
     }
 
@@ -323,7 +325,7 @@
 
 status_t VirtualDisplaySurface::dequeueBuffer(Source source,
         PixelFormat format, uint64_t usage, int* sslot, sp<Fence>* fence) {
-    LOG_FATAL_IF(!mDisplayId);
+    LOG_FATAL_IF(GpuVirtualDisplayId::tryCast(mDisplayId));
 
     status_t result =
             mSource[source]->dequeueBuffer(sslot, fence, mSinkBufferWidth, mSinkBufferHeight,
@@ -369,7 +371,7 @@
                                               PixelFormat format, uint64_t usage,
                                               uint64_t* outBufferAge,
                                               FrameEventHistoryDelta* outTimestamps) {
-    if (!mDisplayId) {
+    if (GpuVirtualDisplayId::tryCast(mDisplayId)) {
         return mSource[SOURCE_SINK]->dequeueBuffer(pslot, fence, w, h, format, usage, outBufferAge,
                                                    outTimestamps);
     }
@@ -456,7 +458,7 @@
 
 status_t VirtualDisplaySurface::queueBuffer(int pslot,
         const QueueBufferInput& input, QueueBufferOutput* output) {
-    if (!mDisplayId) {
+    if (GpuVirtualDisplayId::tryCast(mDisplayId)) {
         return mSource[SOURCE_SINK]->queueBuffer(pslot, input, output);
     }
 
@@ -514,7 +516,7 @@
 
 status_t VirtualDisplaySurface::cancelBuffer(int pslot,
         const sp<Fence>& fence) {
-    if (!mDisplayId) {
+    if (GpuVirtualDisplayId::tryCast(mDisplayId)) {
         return mSource[SOURCE_SINK]->cancelBuffer(mapProducer2SourceSlot(SOURCE_SINK, pslot), fence);
     }
 
@@ -626,7 +628,7 @@
 }
 
 status_t VirtualDisplaySurface::refreshOutputBuffer() {
-    LOG_FATAL_IF(!mDisplayId);
+    LOG_FATAL_IF(GpuVirtualDisplayId::tryCast(mDisplayId));
 
     if (mOutputProducerSlot >= 0) {
         mSource[SOURCE_SINK]->cancelBuffer(
@@ -645,7 +647,9 @@
     // until after GPU calls queueBuffer(). So here we just set the buffer
     // (for use in HWC prepare) but not the fence; we'll call this again with
     // the proper fence once we have it.
-    result = mHwc.setOutputBuffer(*mDisplayId, Fence::NO_FENCE,
+    const auto halDisplayId = HalVirtualDisplayId::tryCast(mDisplayId);
+    LOG_FATAL_IF(!halDisplayId);
+    result = mHwc.setOutputBuffer(*halDisplayId, Fence::NO_FENCE,
                                   mProducerBuffers[mOutputProducerSlot]);
 
     return result;
diff --git a/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.h b/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.h
index 3cbad8f..1974625 100644
--- a/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.h
+++ b/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.h
@@ -24,6 +24,7 @@
 #include <compositionengine/impl/HwcBufferCache.h>
 #include <gui/ConsumerBase.h>
 #include <gui/IGraphicBufferProducer.h>
+#include <ui/DisplayId.h>
 
 #include "DisplayIdentification.h"
 
@@ -77,8 +78,7 @@
                               public BnGraphicBufferProducer,
                               private ConsumerBase {
 public:
-    VirtualDisplaySurface(HWComposer& hwc, const std::optional<DisplayId>& displayId,
-                          const sp<IGraphicBufferProducer>& sink,
+    VirtualDisplaySurface(HWComposer&, VirtualDisplayId, const sp<IGraphicBufferProducer>& sink,
                           const sp<IGraphicBufferProducer>& bqProducer,
                           const sp<IGraphicBufferConsumer>& bqConsumer, const std::string& name);
 
@@ -86,7 +86,7 @@
     // DisplaySurface interface
     //
     virtual status_t beginFrame(bool mustRecompose);
-    virtual status_t prepareFrame(CompositionType compositionType);
+    virtual status_t prepareFrame(CompositionType);
     virtual status_t advanceFrame();
     virtual void onFrameCommitted();
     virtual void dumpAsString(String8& result) const;
@@ -104,25 +104,22 @@
     virtual status_t requestBuffer(int pslot, sp<GraphicBuffer>* outBuf);
     virtual status_t setMaxDequeuedBufferCount(int maxDequeuedBuffers);
     virtual status_t setAsyncMode(bool async);
-    virtual status_t dequeueBuffer(int* pslot, sp<Fence>* fence, uint32_t w, uint32_t h,
-                                   PixelFormat format, uint64_t usage, uint64_t* outBufferAge,
+    virtual status_t dequeueBuffer(int* pslot, sp<Fence>*, uint32_t w, uint32_t h, PixelFormat,
+                                   uint64_t usage, uint64_t* outBufferAge,
                                    FrameEventHistoryDelta* outTimestamps);
     virtual status_t detachBuffer(int slot);
-    virtual status_t detachNextBuffer(sp<GraphicBuffer>* outBuffer,
-            sp<Fence>* outFence);
-    virtual status_t attachBuffer(int* slot, const sp<GraphicBuffer>& buffer);
-    virtual status_t queueBuffer(int pslot,
-            const QueueBufferInput& input, QueueBufferOutput* output);
-    virtual status_t cancelBuffer(int pslot, const sp<Fence>& fence);
+    virtual status_t detachNextBuffer(sp<GraphicBuffer>* outBuffer, sp<Fence>* outFence);
+    virtual status_t attachBuffer(int* slot, const sp<GraphicBuffer>&);
+    virtual status_t queueBuffer(int pslot, const QueueBufferInput&, QueueBufferOutput*);
+    virtual status_t cancelBuffer(int pslot, const sp<Fence>&);
     virtual int query(int what, int* value);
-    virtual status_t connect(const sp<IProducerListener>& listener,
-            int api, bool producerControlledByApp, QueueBufferOutput* output);
-    virtual status_t disconnect(int api, DisconnectMode mode);
+    virtual status_t connect(const sp<IProducerListener>&, int api, bool producerControlledByApp,
+                             QueueBufferOutput*);
+    virtual status_t disconnect(int api, DisconnectMode);
     virtual status_t setSidebandStream(const sp<NativeHandle>& stream);
-    virtual void allocateBuffers(uint32_t width, uint32_t height,
-            PixelFormat format, uint64_t usage);
+    virtual void allocateBuffers(uint32_t width, uint32_t height, PixelFormat, uint64_t usage);
     virtual status_t allowAllocation(bool allow);
-    virtual status_t setGenerationNumber(uint32_t generationNumber);
+    virtual status_t setGenerationNumber(uint32_t);
     virtual String8 getConsumerName() const override;
     virtual status_t setSharedBufferMode(bool sharedBufferMode) override;
     virtual status_t setAutoRefresh(bool autoRefresh) override;
@@ -135,10 +132,9 @@
     //
     // Utility methods
     //
-    static Source fbSourceForCompositionType(CompositionType type);
-    status_t dequeueBuffer(Source source, PixelFormat format, uint64_t usage,
-            int* sslot, sp<Fence>* fence);
-    void updateQueueBufferOutput(QueueBufferOutput&& qbo);
+    static Source fbSourceForCompositionType(CompositionType);
+    status_t dequeueBuffer(Source, PixelFormat, uint64_t usage, int* sslot, sp<Fence>*);
+    void updateQueueBufferOutput(QueueBufferOutput&&);
     void resetPerFrameState();
     status_t refreshOutputBuffer();
 
@@ -148,14 +144,14 @@
     // internally in the VirtualDisplaySurface. To minimize the number of times
     // a producer slot switches which source it comes from, we map source slot
     // numbers to producer slot numbers differently for each source.
-    static int mapSource2ProducerSlot(Source source, int sslot);
-    static int mapProducer2SourceSlot(Source source, int pslot);
+    static int mapSource2ProducerSlot(Source, int sslot);
+    static int mapProducer2SourceSlot(Source, int pslot);
 
     //
     // Immutable after construction
     //
     HWComposer& mHwc;
-    const std::optional<DisplayId> mDisplayId;
+    const VirtualDisplayId mDisplayId;
     const std::string mDisplayName;
     sp<IGraphicBufferProducer> mSource[2]; // indexed by SOURCE_*
     uint32_t mDefaultOutputFormat;
diff --git a/services/surfaceflinger/DisplayIdGenerator.h b/services/surfaceflinger/DisplayIdGenerator.h
new file mode 100644
index 0000000..e7c69a8
--- /dev/null
+++ b/services/surfaceflinger/DisplayIdGenerator.h
@@ -0,0 +1,75 @@
+/*
+ * Copyright 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <ui/DisplayId.h>
+
+#include <limits>
+#include <optional>
+#include <random>
+#include <unordered_set>
+
+#include <log/log.h>
+
+namespace android {
+
+template <typename T>
+class DisplayIdGenerator {
+public:
+    virtual std::optional<T> nextId() = 0;
+    virtual void markUnused(T id) = 0;
+
+protected:
+    ~DisplayIdGenerator() {}
+};
+
+template <typename T>
+class RandomDisplayIdGenerator final : public DisplayIdGenerator<T> {
+public:
+    explicit RandomDisplayIdGenerator(size_t maxIdsCount = std::numeric_limits<size_t>::max())
+          : mMaxIdsCount(maxIdsCount) {}
+
+    std::optional<T> nextId() override {
+        if (mUsedIds.size() >= mMaxIdsCount) {
+            return std::nullopt;
+        }
+
+        constexpr int kMaxAttempts = 1000;
+
+        for (int attempts = 0; attempts < kMaxAttempts; attempts++) {
+            const auto baseId = mDistribution(mGenerator);
+            const T id(baseId);
+            if (mUsedIds.count(id) == 0) {
+                mUsedIds.insert(id);
+                return id;
+            }
+        }
+
+        LOG_ALWAYS_FATAL("Couldn't generate ID after %d attempts", kMaxAttempts);
+    }
+
+    void markUnused(T id) override { mUsedIds.erase(id); }
+
+private:
+    const size_t mMaxIdsCount;
+
+    std::unordered_set<T> mUsedIds;
+    std::default_random_engine mGenerator{std::random_device()()};
+    std::uniform_int_distribution<typename T::BaseId> mDistribution;
+};
+
+} // namespace android
\ No newline at end of file
diff --git a/services/surfaceflinger/FrameTimeline/FrameTimeline.cpp b/services/surfaceflinger/FrameTimeline/FrameTimeline.cpp
index a12f4c7..9985253 100644
--- a/services/surfaceflinger/FrameTimeline/FrameTimeline.cpp
+++ b/services/surfaceflinger/FrameTimeline/FrameTimeline.cpp
@@ -20,6 +20,7 @@
 
 #include "FrameTimeline.h"
 #include <android-base/stringprintf.h>
+#include <utils/Log.h>
 #include <utils/Trace.h>
 #include <cinttypes>
 
@@ -104,9 +105,9 @@
     std::lock_guard<std::mutex> lock(mMutex);
     mActualQueueTime = actualQueueTime;
 }
-void SurfaceFrame::setActualEndTime(nsecs_t actualEndTime) {
+void SurfaceFrame::setAcquireFenceTime(nsecs_t acquireFenceTime) {
     std::lock_guard<std::mutex> lock(mMutex);
-    mActuals.endTime = actualEndTime;
+    mActuals.endTime = std::max(acquireFenceTime, mActualQueueTime);
 }
 
 void SurfaceFrame::setActualPresentTime(nsecs_t presentTime) {
diff --git a/services/surfaceflinger/FrameTimeline/FrameTimeline.h b/services/surfaceflinger/FrameTimeline/FrameTimeline.h
index 9d7b540..6d1bb73 100644
--- a/services/surfaceflinger/FrameTimeline/FrameTimeline.h
+++ b/services/surfaceflinger/FrameTimeline/FrameTimeline.h
@@ -92,10 +92,10 @@
 
     // Actual timestamps of the app are set individually at different functions.
     // Start time (if the app provides) and Queue time are accessible after queueing the frame,
-    // whereas End time is available only during latch.
+    // whereas Acquire Fence time is available only during latch.
     virtual void setActualStartTime(nsecs_t actualStartTime) = 0;
     virtual void setActualQueueTime(nsecs_t actualQueueTime) = 0;
-    virtual void setActualEndTime(nsecs_t actualEndTime) = 0;
+    virtual void setAcquireFenceTime(nsecs_t acquireFenceTime) = 0;
 };
 
 /*
@@ -170,7 +170,7 @@
 
     void setActualStartTime(nsecs_t actualStartTime) override;
     void setActualQueueTime(nsecs_t actualQueueTime) override;
-    void setActualEndTime(nsecs_t actualEndTime) override;
+    void setAcquireFenceTime(nsecs_t acquireFenceTime) override;
     void setPresentState(PresentState state) override;
     void setActualPresentTime(nsecs_t presentTime);
     void dump(std::string& result);
diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index df2ef80..08801c9 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -894,7 +894,10 @@
         auto surfaceFrame =
                 mFlinger->mFrameTimeline->createSurfaceFrameForToken(mTransactionName, vsyncId);
         surfaceFrame->setActualQueueTime(stateToCommit->postTime);
-        surfaceFrame->setActualEndTime(stateToCommit->postTime);
+        // For transactions we set the acquire fence time to the post time as we
+        // don't have a buffer. For BufferStateLayer it is overridden in
+        // BufferStateLayer::applyPendingStates
+        surfaceFrame->setAcquireFenceTime(stateToCommit->postTime);
 
         mSurfaceFrame = std::move(surfaceFrame);
     }
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 1b15164..363d29e 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -328,7 +328,7 @@
 
 SurfaceFlinger::SurfaceFlinger(Factory& factory, SkipInitializationTag)
       : mFactory(factory),
-        mInterceptor(mFactory.createSurfaceInterceptor(this)),
+        mInterceptor(mFactory.createSurfaceInterceptor()),
         mTimeStats(std::make_shared<impl::TimeStats>()),
         mFrameTracer(std::make_unique<FrameTracer>()),
         mFrameTimeline(std::make_unique<frametimeline::impl::FrameTimeline>()),
@@ -717,7 +717,8 @@
     processDisplayHotplugEventsLocked();
     const auto display = getDefaultDisplayDeviceLocked();
     LOG_ALWAYS_FATAL_IF(!display, "Missing internal display after registering composer callback.");
-    LOG_ALWAYS_FATAL_IF(!getHwComposer().isConnected(*display->getId()),
+    const auto displayId = display->getPhysicalId();
+    LOG_ALWAYS_FATAL_IF(!getHwComposer().isConnected(displayId),
                         "Internal display is disconnected.");
 
     // initialize our drawing state
@@ -1078,8 +1079,8 @@
         const nsecs_t vsyncPeriod =
                 mRefreshRateConfigs->getRefreshRateFromConfigId(mUpcomingActiveConfig.configId)
                         .getVsyncPeriod();
-        mScheduler->onPrimaryDisplayConfigChanged(mAppConnectionHandle,
-                                                  static_cast<PhysicalDisplayId>(*display->getId()),
+        const auto physicalId = display->getPhysicalId();
+        mScheduler->onPrimaryDisplayConfigChanged(mAppConnectionHandle, physicalId,
                                                   mUpcomingActiveConfig.configId, vsyncPeriod);
     }
 }
@@ -1128,8 +1129,7 @@
     }
 
     mUpcomingActiveConfig = *desiredActiveConfig;
-    const auto displayId = display->getId();
-    LOG_ALWAYS_FATAL_IF(!displayId);
+    const auto displayId = display->getPhysicalId();
 
     ATRACE_INT("ActiveConfigFPS_HWC", refreshRate.getFps());
 
@@ -1140,7 +1140,7 @@
 
     hal::VsyncPeriodChangeTimeline outTimeline;
     auto status =
-            getHwComposer().setActiveConfigWithConstraints(*displayId,
+            getHwComposer().setActiveConfigWithConstraints(displayId,
                                                            mUpcomingActiveConfig.configId.value(),
                                                            constraints, &outTimeline);
     if (status != NO_ERROR) {
@@ -1665,7 +1665,7 @@
 
         if (const auto display = getDefaultDisplayDeviceLocked();
             display && display->isPoweredOn()) {
-            getHwComposer().setVsyncEnabled(*display->getId(), mHWCVsyncPendingState);
+            getHwComposer().setVsyncEnabled(display->getPhysicalId(), mHWCVsyncPendingState);
         }
     }));
 }
@@ -2120,7 +2120,7 @@
     getBE().mDisplayTimeline.updateSignalTimes();
     mPreviousPresentFences[1] = mPreviousPresentFences[0];
     mPreviousPresentFences[0] =
-            display ? getHwComposer().getPresentFence(*display->getId()) : Fence::NO_FENCE;
+            display ? getHwComposer().getPresentFence(display->getPhysicalId()) : Fence::NO_FENCE;
     auto presentFenceTime = std::make_shared<FenceTime>(mPreviousPresentFences[0]);
     getBE().mDisplayTimeline.push(presentFenceTime);
 
@@ -2154,7 +2154,8 @@
         mScheduler->addPresentFence(presentFenceTime);
     }
 
-    const bool isDisplayConnected = display && getHwComposer().isConnected(*display->getId());
+    const bool isDisplayConnected =
+            display && getHwComposer().isConnected(display->getPhysicalId());
 
     if (!hasSyncFramework) {
         if (isDisplayConnected && display->isPoweredOn()) {
@@ -2171,7 +2172,8 @@
         } else if (isDisplayConnected) {
             // The HWC doesn't support present fences, so use the refresh
             // timestamp instead.
-            const nsecs_t presentTime = getHwComposer().getRefreshTimestamp(*display->getId());
+            const nsecs_t presentTime =
+                    getHwComposer().getRefreshTimestamp(display->getPhysicalId());
             mAnimFrameTracker.setActualPresentTime(presentTime);
         }
         mAnimFrameTracker.advanceFrame();
@@ -2273,7 +2275,7 @@
 
 void SurfaceFlinger::postFrame() {
     const auto display = ON_MAIN_THREAD(getDefaultDisplayDeviceLocked());
-    if (display && getHwComposer().isConnected(*display->getId())) {
+    if (display && getHwComposer().isConnected(display->getPhysicalId())) {
         uint32_t flipCount = display->getPageFlipCount();
         if (flipCount % LOG_FRAME_STATS_PERIOD == 0) {
             logFrameStats();
@@ -2378,7 +2380,6 @@
         const DisplayDeviceState& state,
         const sp<compositionengine::DisplaySurface>& displaySurface,
         const sp<IGraphicBufferProducer>& producer) {
-    auto displayId = compositionDisplay->getDisplayId();
     DisplayDeviceCreationArgs creationArgs(this, displayToken, compositionDisplay);
     creationArgs.sequenceId = state.sequenceId;
     creationArgs.isSecure = state.isSecure;
@@ -2390,26 +2391,26 @@
         creationArgs.connectionType = physical->type;
     }
 
-    const bool isInternalDisplay = displayId && displayId == getInternalDisplayIdLocked();
-    creationArgs.isPrimary = isInternalDisplay;
+    if (const auto id = PhysicalDisplayId::tryCast(compositionDisplay->getId())) {
+        creationArgs.isPrimary = id == getInternalDisplayIdLocked();
 
-    if (useColorManagement && displayId) {
-        std::vector<ColorMode> modes = getHwComposer().getColorModes(*displayId);
-        for (ColorMode colorMode : modes) {
-            if (isWideColorMode(colorMode)) {
-                creationArgs.hasWideColorGamut = true;
+        if (useColorManagement) {
+            std::vector<ColorMode> modes = getHwComposer().getColorModes(*id);
+            for (ColorMode colorMode : modes) {
+                if (isWideColorMode(colorMode)) {
+                    creationArgs.hasWideColorGamut = true;
+                }
+
+                std::vector<RenderIntent> renderIntents =
+                        getHwComposer().getRenderIntents(*id, colorMode);
+                creationArgs.hwcColorModes.emplace(colorMode, renderIntents);
             }
-
-            std::vector<RenderIntent> renderIntents =
-                    getHwComposer().getRenderIntents(*displayId, colorMode);
-            creationArgs.hwcColorModes.emplace(colorMode, renderIntents);
         }
     }
 
-    if (displayId) {
-        getHwComposer().getHdrCapabilities(*displayId, &creationArgs.hdrCapabilities);
-        creationArgs.supportedPerFrameMetadata =
-                getHwComposer().getSupportedPerFrameMetadata(*displayId);
+    if (const auto id = HalDisplayId::tryCast(compositionDisplay->getId())) {
+        getHwComposer().getHdrCapabilities(*id, &creationArgs.hdrCapabilities);
+        creationArgs.supportedPerFrameMetadata = getHwComposer().getSupportedPerFrameMetadata(*id);
     }
 
     auto nativeWindowSurface = getFactory().createNativeWindowSurface(producer);
@@ -2424,7 +2425,7 @@
     }
 
     creationArgs.physicalOrientation =
-            isInternalDisplay ? internalDisplayOrientation : ui::ROTATION_0;
+            creationArgs.isPrimary ? internalDisplayOrientation : ui::ROTATION_0;
 
     // virtual displays are always considered enabled
     creationArgs.initialPowerMode = state.isVirtual() ? hal::PowerMode::ON : hal::PowerMode::OFF;
@@ -2446,8 +2447,8 @@
                                                     RenderIntent::COLORIMETRIC,
                                                     Dataspace::UNKNOWN});
     if (!state.isVirtual()) {
-        LOG_ALWAYS_FATAL_IF(!displayId);
-        auto activeConfigId = HwcConfigIndexType(getHwComposer().getActiveConfigIndex(*displayId));
+        const auto physicalId = display->getPhysicalId();
+        auto activeConfigId = HwcConfigIndexType(getHwComposer().getActiveConfigIndex(physicalId));
         display->setActiveConfig(activeConfigId);
         display->setDeviceProductInfo(state.physical->deviceProductInfo);
     }
@@ -2497,6 +2498,7 @@
     builder.setLayerStackId(state.layerStack);
     builder.setPowerAdvisor(&mPowerAdvisor);
     builder.setUseHwcVirtualDisplays(mUseHwcVirtualDisplays);
+    builder.setGpuVirtualDisplayIdGenerator(mGpuVirtualDisplayIdGenerator);
     builder.setName(state.displayName);
     const auto compositionDisplay = getCompositionEngine().createDisplay(builder.build());
 
@@ -2506,11 +2508,13 @@
     sp<IGraphicBufferConsumer> bqConsumer;
     getFactory().createBufferQueue(&bqProducer, &bqConsumer, /*consumerIsSurfaceFlinger =*/false);
 
-    std::optional<DisplayId> displayId = compositionDisplay->getId();
+    DisplayId displayId = compositionDisplay->getId();
 
     if (state.isVirtual()) {
+        const auto virtualId = VirtualDisplayId::tryCast(displayId);
+        LOG_FATAL_IF(!virtualId);
         sp<VirtualDisplaySurface> vds =
-                new VirtualDisplaySurface(getHwComposer(), displayId, state.surface, bqProducer,
+                new VirtualDisplaySurface(getHwComposer(), *virtualId, state.surface, bqProducer,
                                           bqConsumer, state.displayName);
 
         displaySurface = vds;
@@ -2520,9 +2524,9 @@
                  "adding a supported display, but rendering "
                  "surface is provided (%p), ignoring it",
                  state.surface.get());
-
-        LOG_ALWAYS_FATAL_IF(!displayId);
-        displaySurface = new FramebufferSurface(getHwComposer(), *displayId, bqConsumer,
+        const auto physicalId = PhysicalDisplayId::tryCast(displayId);
+        LOG_FATAL_IF(!physicalId);
+        displaySurface = new FramebufferSurface(getHwComposer(), *physicalId, bqConsumer,
                                                 maxGraphicsWidth, maxGraphicsHeight);
         producer = bqProducer;
     }
@@ -2532,8 +2536,7 @@
                                                        displaySurface, producer);
     mDisplays.emplace(displayToken, display);
     if (!state.isVirtual()) {
-        LOG_FATAL_IF(!displayId);
-        dispatchDisplayHotplugEvent(static_cast<PhysicalDisplayId>(*displayId), true);
+        dispatchDisplayHotplugEvent(display->getPhysicalId(), true);
     }
 
     if (display->isPrimary()) {
@@ -2543,13 +2546,9 @@
 
 void SurfaceFlinger::processDisplayRemoved(const wp<IBinder>& displayToken) {
     if (const auto display = getDisplayDeviceLocked(displayToken)) {
-        // Save display ID before disconnecting.
-        const auto displayId = display->getId();
         display->disconnect();
-
         if (!display->isVirtual()) {
-            LOG_FATAL_IF(!displayId);
-            dispatchDisplayHotplugEvent(static_cast<PhysicalDisplayId>(*displayId), false);
+            dispatchDisplayHotplugEvent(display->getPhysicalId(), false);
         }
     }
 
@@ -2825,7 +2824,7 @@
 void SurfaceFlinger::updateCursorAsync() {
     compositionengine::CompositionRefreshArgs refreshArgs;
     for (const auto& [_, display] : ON_MAIN_THREAD(mDisplays)) {
-        if (display->getId()) {
+        if (HalDisplayId::tryCast(display->getId())) {
             refreshArgs.outputs.push_back(display->getCompositionDisplay());
         }
     }
@@ -3303,7 +3302,7 @@
     applyTransactionState(frameTimelineVsyncId, states, displays, flags, inputWindowCommands,
                           desiredPresentTime, uncacheBuffer, postTime, privileged,
                           hasListenerCallbacks, listenerCallbacks, originPid, originUid,
-                          /*isMainThread*/ false);
+                          transactionId, /*isMainThread*/ false);
     return NO_ERROR;
 }
 
@@ -3596,7 +3595,8 @@
         const auto& p = layer->getParent();
         if (p == nullptr) {
             ssize_t idx = mCurrentState.layersSortedByZ.indexOf(layer);
-            if (layer->setRelativeLayer(s.relativeLayerHandle, s.z) && idx >= 0) {
+            if (layer->setRelativeLayer(s.relativeLayerSurfaceControl->getHandle(), s.z) &&
+                idx >= 0) {
                 mCurrentState.layersSortedByZ.removeAt(idx);
                 mCurrentState.layersSortedByZ.add(layer);
                 // we need traversal (state changed)
@@ -3604,7 +3604,7 @@
                 flags |= eTransactionNeeded|eTraversalNeeded;
             }
         } else {
-            if (p->setChildRelativeLayer(layer, s.relativeLayerHandle, s.z)) {
+            if (p->setChildRelativeLayer(layer, s.relativeLayerSurfaceControl->getHandle(), s.z)) {
                 flags |= eTransactionNeeded|eTraversalNeeded;
             }
         }
@@ -3690,24 +3690,13 @@
         }
     }
     if (what & layer_state_t::eDeferTransaction_legacy) {
-        if (s.barrierHandle_legacy != nullptr) {
-            layer->deferTransactionUntil_legacy(s.barrierHandle_legacy, s.barrierFrameNumber);
-        } else if (s.barrierGbp_legacy != nullptr) {
-            const sp<IGraphicBufferProducer>& gbp = s.barrierGbp_legacy;
-            if (authenticateSurfaceTextureLocked(gbp)) {
-                const auto& otherLayer =
-                    (static_cast<MonitoredProducer*>(gbp.get()))->getLayer();
-                layer->deferTransactionUntil_legacy(otherLayer, s.barrierFrameNumber);
-            } else {
-                ALOGE("Attempt to defer transaction to to an"
-                        " unrecognized GraphicBufferProducer");
-            }
-        }
+        layer->deferTransactionUntil_legacy(s.barrierSurfaceControl_legacy->getHandle(),
+                                            s.barrierFrameNumber);
         // We don't trigger a traversal here because if no other state is
         // changed, we don't want this to cause any more work
     }
     if (what & layer_state_t::eReparentChildren) {
-        if (layer->reparentChildren(s.reparentHandle)) {
+        if (layer->reparentChildren(s.reparentSurfaceControl->getHandle())) {
             flags |= eTransactionNeeded|eTraversalNeeded;
         }
     }
@@ -3794,7 +3783,10 @@
     // lose its relative z order.
     if (what & layer_state_t::eReparent) {
         bool hadParent = layer->hasParent();
-        if (layer->reparent(s.parentHandleForChild)) {
+        auto parentHandle = (s.parentSurfaceControlForChild)
+                ? s.parentSurfaceControlForChild->getHandle()
+                : nullptr;
+        if (layer->reparent(parentHandle)) {
             if (!hadParent) {
                 mCurrentState.layersSortedByZ.remove(layer);
             }
@@ -4132,10 +4124,8 @@
         return;
     }
 
-    const auto displayId = display->getId();
-    LOG_ALWAYS_FATAL_IF(!displayId);
-
-    ALOGD("Setting power mode %d on display %s", mode, to_string(*displayId).c_str());
+    const auto displayId = display->getPhysicalId();
+    ALOGD("Setting power mode %d on display %s", mode, to_string(displayId).c_str());
 
     const hal::PowerMode currentMode = display->getPowerMode();
     if (mode == currentMode) {
@@ -4152,9 +4142,9 @@
         if (SurfaceFlinger::setSchedFifo(true) != NO_ERROR) {
             ALOGW("Couldn't set SCHED_FIFO on display on: %s\n", strerror(errno));
         }
-        getHwComposer().setPowerMode(*displayId, mode);
+        getHwComposer().setPowerMode(displayId, mode);
         if (display->isPrimary() && mode != hal::PowerMode::DOZE_SUSPEND) {
-            getHwComposer().setVsyncEnabled(*displayId, mHWCVsyncPendingState);
+            getHwComposer().setVsyncEnabled(displayId, mHWCVsyncPendingState);
             mScheduler->onScreenAcquired(mAppConnectionHandle);
             mScheduler->resyncToHardwareVsync(true, vsyncPeriod);
         }
@@ -4173,14 +4163,14 @@
         }
 
         // Make sure HWVsync is disabled before turning off the display
-        getHwComposer().setVsyncEnabled(*displayId, hal::Vsync::DISABLE);
+        getHwComposer().setVsyncEnabled(displayId, hal::Vsync::DISABLE);
 
-        getHwComposer().setPowerMode(*displayId, mode);
+        getHwComposer().setPowerMode(displayId, mode);
         mVisibleRegionsDirty = true;
         // from this point on, SF will stop drawing on this display
     } else if (mode == hal::PowerMode::DOZE || mode == hal::PowerMode::ON) {
         // Update display while dozing
-        getHwComposer().setPowerMode(*displayId, mode);
+        getHwComposer().setPowerMode(displayId, mode);
         if (display->isPrimary() && currentMode == hal::PowerMode::DOZE_SUSPEND) {
             mScheduler->onScreenAcquired(mAppConnectionHandle);
             mScheduler->resyncToHardwareVsync(true, vsyncPeriod);
@@ -4191,10 +4181,10 @@
             mScheduler->disableHardwareVsync(true);
             mScheduler->onScreenReleased(mAppConnectionHandle);
         }
-        getHwComposer().setPowerMode(*displayId, mode);
+        getHwComposer().setPowerMode(displayId, mode);
     } else {
         ALOGE("Attempting to set unknown power mode: %d\n", mode);
-        getHwComposer().setPowerMode(*displayId, mode);
+        getHwComposer().setPowerMode(displayId, mode);
     }
 
     if (display->isPrimary()) {
@@ -4203,7 +4193,7 @@
         mScheduler->setDisplayPowerState(mode == hal::PowerMode::ON);
     }
 
-    ALOGD("Finished setting power mode %d on display %s", mode, to_string(*displayId).c_str());
+    ALOGD("Finished setting power mode %d on display %s", mode, to_string(displayId).c_str());
 }
 
 void SurfaceFlinger::setPowerMode(const sp<IBinder>& displayToken, int mode) {
@@ -4462,12 +4452,11 @@
 
 void SurfaceFlinger::dumpDisplayIdentificationData(std::string& result) const {
     for (const auto& [token, display] : mDisplays) {
-        const auto displayId = display->getId();
+        const auto displayId = PhysicalDisplayId::tryCast(display->getId());
         if (!displayId) {
             continue;
         }
-        const auto hwcDisplayId =
-                getHwComposer().fromPhysicalDisplayId(static_cast<PhysicalDisplayId>(*displayId));
+        const auto hwcDisplayId = getHwComposer().fromPhysicalDisplayId(*displayId);
         if (!hwcDisplayId) {
             continue;
         }
@@ -4520,7 +4509,7 @@
     // TODO: print out if wide-color mode is active or not
 
     for (const auto& [token, display] : mDisplays) {
-        const auto displayId = display->getId();
+        const auto displayId = PhysicalDisplayId::tryCast(display->getId());
         if (!displayId) {
             continue;
         }
@@ -4734,7 +4723,7 @@
      * HWC layer minidump
      */
     for (const auto& [token, display] : mDisplays) {
-        const auto displayId = display->getId();
+        const auto displayId = HalDisplayId::tryCast(display->getId());
         if (!displayId) {
             continue;
         }
@@ -5253,18 +5242,12 @@
             // Inject a hotplug connected event for the primary display. This will deallocate and
             // reallocate the display state including framebuffers.
             case 1037: {
-                const auto token = getInternalDisplayToken();
-
-                sp<DisplayDevice> display;
+                std::optional<hal::HWDisplayId> hwcId;
                 {
                     Mutex::Autolock lock(mStateLock);
-                    display = getDisplayDeviceLocked(token);
+                    hwcId = getHwComposer().getInternalHwcDisplayId();
                 }
-                const auto hwcId =
-                        getHwComposer().fromPhysicalDisplayId(PhysicalDisplayId(*display->getId()));
-
                 onHotplugReceived(getBE().mComposerSequenceId, *hwcId, hal::Connection::CONNECTED);
-
                 return NO_ERROR;
             }
         }
@@ -5871,16 +5854,14 @@
         // as well. For now, just call directly to setActiveConfigWithConstraints but ideally
         // it should go thru setDesiredActiveConfig, similar to primary display.
         ALOGV("setAllowedDisplayConfigsInternal for non-primary display");
-        const auto displayId = display->getId();
-        LOG_ALWAYS_FATAL_IF(!displayId);
+        const auto displayId = display->getPhysicalId();
 
         hal::VsyncPeriodChangeConstraints constraints;
         constraints.desiredTimeNanos = systemTime();
         constraints.seamlessRequired = false;
 
         hal::VsyncPeriodChangeTimeline timeline = {0, 0, 0};
-        if (getHwComposer().setActiveConfigWithConstraints(*displayId,
-                                                           policy->defaultConfig.value(),
+        if (getHwComposer().setActiveConfigWithConstraints(displayId, policy->defaultConfig.value(),
                                                            constraints, &timeline) < 0) {
             return BAD_VALUE;
         }
@@ -5890,11 +5871,9 @@
 
         display->setActiveConfig(policy->defaultConfig);
         const nsecs_t vsyncPeriod = getHwComposer()
-                                            .getConfigs(*displayId)[policy->defaultConfig.value()]
+                                            .getConfigs(displayId)[policy->defaultConfig.value()]
                                             ->getVsyncPeriod();
-        mScheduler->onNonPrimaryDisplayConfigChanged(mAppConnectionHandle,
-                                                     static_cast<PhysicalDisplayId>(
-                                                             *display->getId()),
+        mScheduler->onNonPrimaryDisplayConfigChanged(mAppConnectionHandle, displayId,
                                                      policy->defaultConfig, vsyncPeriod);
         return NO_ERROR;
     }
@@ -5926,8 +5905,8 @@
     const nsecs_t vsyncPeriod =
             mRefreshRateConfigs->getRefreshRateFromConfigId(display->getActiveConfig())
                     .getVsyncPeriod();
-    mScheduler->onPrimaryDisplayConfigChanged(mAppConnectionHandle,
-                                              static_cast<PhysicalDisplayId>(*display->getId()),
+    const auto physicalId = display->getPhysicalId();
+    mScheduler->onPrimaryDisplayConfigChanged(mAppConnectionHandle, physicalId,
                                               display->getActiveConfig(), vsyncPeriod);
     toggleKernelIdleTimer();
 
@@ -6018,11 +5997,9 @@
     } else if (display->isVirtual()) {
         return INVALID_OPERATION;
     } else {
-        const auto displayId = display->getId();
-        LOG_FATAL_IF(!displayId);
-
-        *outDefaultConfig = getHwComposer().getActiveConfigIndex(*displayId);
-        auto vsyncPeriod = getHwComposer().getActiveConfig(*displayId)->getVsyncPeriod();
+        const auto displayId = display->getPhysicalId();
+        *outDefaultConfig = getHwComposer().getActiveConfigIndex(displayId);
+        auto vsyncPeriod = getHwComposer().getActiveConfig(displayId)->getVsyncPeriod();
         *outPrimaryRefreshRateMin = 1e9f / vsyncPeriod;
         *outPrimaryRefreshRateMax = 1e9f / vsyncPeriod;
         *outAppRequestRefreshRateMin = 1e9f / vsyncPeriod;
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index 66acde0..aba07b7 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -52,6 +52,7 @@
 #include "DisplayDevice.h"
 #include "DisplayHardware/HWC2.h"
 #include "DisplayHardware/PowerAdvisor.h"
+#include "DisplayIdGenerator.h"
 #include "Effects/Daltonizer.h"
 #include "FrameTracker.h"
 #include "LayerVector.h"
@@ -948,8 +949,8 @@
         return it != mPhysicalDisplayTokens.end() ? it->second : nullptr;
     }
 
-    std::optional<DisplayId> getPhysicalDisplayIdLocked(const sp<IBinder>& displayToken) const
-            REQUIRES(mStateLock) {
+    std::optional<PhysicalDisplayId> getPhysicalDisplayIdLocked(
+            const sp<IBinder>& displayToken) const REQUIRES(mStateLock) {
         for (const auto& [id, token] : mPhysicalDisplayTokens) {
             if (token == displayToken) {
                 return id;
@@ -1112,6 +1113,8 @@
     std::unordered_map<PhysicalDisplayId, sp<IBinder>> mPhysicalDisplayTokens
             GUARDED_BY(mStateLock);
 
+    RandomDisplayIdGenerator<GpuVirtualDisplayId> mGpuVirtualDisplayIdGenerator;
+
     std::unordered_map<BBinder*, wp<Layer>> mLayersByLocalBinderToken GUARDED_BY(mStateLock);
 
     // don't use a lock for these, we don't care
diff --git a/services/surfaceflinger/SurfaceFlingerDefaultFactory.cpp b/services/surfaceflinger/SurfaceFlingerDefaultFactory.cpp
index 93d36a6..9a8deae 100644
--- a/services/surfaceflinger/SurfaceFlingerDefaultFactory.cpp
+++ b/services/surfaceflinger/SurfaceFlingerDefaultFactory.cpp
@@ -68,8 +68,8 @@
     return std::make_unique<Scheduler>(configs, callback);
 }
 
-sp<SurfaceInterceptor> DefaultFactory::createSurfaceInterceptor(SurfaceFlinger* flinger) {
-    return new android::impl::SurfaceInterceptor(flinger);
+sp<SurfaceInterceptor> DefaultFactory::createSurfaceInterceptor() {
+    return new android::impl::SurfaceInterceptor();
 }
 
 sp<StartPropertySetThread> DefaultFactory::createStartPropertySetThread(
diff --git a/services/surfaceflinger/SurfaceFlingerDefaultFactory.h b/services/surfaceflinger/SurfaceFlingerDefaultFactory.h
index e06c2f4..40774ef 100644
--- a/services/surfaceflinger/SurfaceFlingerDefaultFactory.h
+++ b/services/surfaceflinger/SurfaceFlingerDefaultFactory.h
@@ -32,7 +32,7 @@
             const scheduler::RefreshRateConfigs&) override;
     std::unique_ptr<Scheduler> createScheduler(const scheduler::RefreshRateConfigs&,
                                                ISchedulerCallback&) override;
-    sp<SurfaceInterceptor> createSurfaceInterceptor(SurfaceFlinger*) override;
+    sp<SurfaceInterceptor> createSurfaceInterceptor() override;
     sp<StartPropertySetThread> createStartPropertySetThread(bool timestampPropertyValue) override;
     sp<DisplayDevice> createDisplayDevice(DisplayDeviceCreationArgs&) override;
     sp<GraphicBuffer> createGraphicBuffer(uint32_t width, uint32_t height, PixelFormat format,
diff --git a/services/surfaceflinger/SurfaceFlingerFactory.h b/services/surfaceflinger/SurfaceFlingerFactory.h
index 41ccc10..2dd563b 100644
--- a/services/surfaceflinger/SurfaceFlingerFactory.h
+++ b/services/surfaceflinger/SurfaceFlingerFactory.h
@@ -73,7 +73,7 @@
             const scheduler::RefreshRateConfigs&) = 0;
     virtual std::unique_ptr<Scheduler> createScheduler(const scheduler::RefreshRateConfigs&,
                                                        ISchedulerCallback&) = 0;
-    virtual sp<SurfaceInterceptor> createSurfaceInterceptor(SurfaceFlinger*) = 0;
+    virtual sp<SurfaceInterceptor> createSurfaceInterceptor() = 0;
 
     virtual sp<StartPropertySetThread> createStartPropertySetThread(
             bool timestampPropertyValue) = 0;
diff --git a/services/surfaceflinger/SurfaceInterceptor.cpp b/services/surfaceflinger/SurfaceInterceptor.cpp
index 4407f4c..da58d4e 100644
--- a/services/surfaceflinger/SurfaceInterceptor.cpp
+++ b/services/surfaceflinger/SurfaceInterceptor.cpp
@@ -40,11 +40,6 @@
 
 namespace impl {
 
-SurfaceInterceptor::SurfaceInterceptor(SurfaceFlinger* flinger)
-    :   mFlinger(flinger)
-{
-}
-
 void SurfaceInterceptor::addTransactionTraceListener(
         const sp<gui::ITransactionTraceListener>& listener) {
     sp<IBinder> asBinder = IInterface::asBinder(listener);
@@ -472,16 +467,10 @@
     }
     if (state.what & layer_state_t::eDeferTransaction_legacy) {
         sp<Layer> otherLayer = nullptr;
-        if (state.barrierHandle_legacy != nullptr) {
-            otherLayer =
-                    static_cast<Layer::Handle*>(state.barrierHandle_legacy.get())->owner.promote();
-        } else if (state.barrierGbp_legacy != nullptr) {
-            auto const& gbp = state.barrierGbp_legacy;
-            if (mFlinger->authenticateSurfaceTextureLocked(gbp)) {
-                otherLayer = (static_cast<MonitoredProducer*>(gbp.get()))->getLayer();
-            } else {
-                ALOGE("Attempt to defer transaction to to an unrecognized GraphicBufferProducer");
-            }
+        if (state.barrierSurfaceControl_legacy != nullptr) {
+            otherLayer = static_cast<Layer::Handle*>(
+                                 state.barrierSurfaceControl_legacy->getHandle().get())
+                                 ->owner.promote();
         }
         addDeferTransactionLocked(transaction, layerId, otherLayer, state.barrierFrameNumber);
     }
@@ -489,17 +478,23 @@
         addOverrideScalingModeLocked(transaction, layerId, state.overrideScalingMode);
     }
     if (state.what & layer_state_t::eReparent) {
-        addReparentLocked(transaction, layerId, getLayerIdFromHandle(state.parentHandleForChild));
+        auto parentHandle = (state.parentSurfaceControlForChild)
+                ? state.parentSurfaceControlForChild->getHandle()
+                : nullptr;
+        addReparentLocked(transaction, layerId, getLayerIdFromHandle(parentHandle));
     }
     if (state.what & layer_state_t::eReparentChildren) {
-        addReparentChildrenLocked(transaction, layerId, getLayerIdFromHandle(state.reparentHandle));
+        addReparentChildrenLocked(transaction, layerId,
+                                  getLayerIdFromHandle(state.reparentSurfaceControl->getHandle()));
     }
     if (state.what & layer_state_t::eDetachChildren) {
         addDetachChildrenLocked(transaction, layerId, true);
     }
     if (state.what & layer_state_t::eRelativeLayerChanged) {
         addRelativeParentLocked(transaction, layerId,
-                                getLayerIdFromHandle(state.relativeLayerHandle), state.z);
+                                getLayerIdFromHandle(
+                                        state.relativeLayerSurfaceControl->getHandle()),
+                                state.z);
     }
     if (state.what & layer_state_t::eShadowRadiusChanged) {
         addShadowRadiusLocked(transaction, layerId, state.shadowRadius);
diff --git a/services/surfaceflinger/SurfaceInterceptor.h b/services/surfaceflinger/SurfaceInterceptor.h
index 46284df..9ac189a 100644
--- a/services/surfaceflinger/SurfaceInterceptor.h
+++ b/services/surfaceflinger/SurfaceInterceptor.h
@@ -92,7 +92,7 @@
  */
 class SurfaceInterceptor final : public android::SurfaceInterceptor {
 public:
-    explicit SurfaceInterceptor(SurfaceFlinger* const flinger);
+    SurfaceInterceptor() = default;
     ~SurfaceInterceptor() override = default;
 
     // Both vectors are used to capture the current state of SF as the initial snapshot in the trace
@@ -202,7 +202,6 @@
     std::string mOutputFileName {DEFAULT_FILENAME};
     std::mutex mTraceMutex {};
     Trace mTrace {};
-    SurfaceFlinger* const mFlinger;
     std::mutex mListenersMutex;
     std::map<wp<IBinder>, sp<gui::ITransactionTraceListener>> mTraceToggledListeners
             GUARDED_BY(mListenersMutex);
diff --git a/services/surfaceflinger/tests/DetachChildren_test.cpp b/services/surfaceflinger/tests/DetachChildren_test.cpp
index 3261308..9c7b1fc 100644
--- a/services/surfaceflinger/tests/DetachChildren_test.cpp
+++ b/services/surfaceflinger/tests/DetachChildren_test.cpp
@@ -61,7 +61,7 @@
     TransactionUtils::fillSurfaceRGBA8(relative, relativeColor);
 
     Transaction{}
-            .setRelativeLayer(relative, mMainSurface->getHandle(), 1)
+            .setRelativeLayer(relative, mMainSurface, 1)
             .setPosition(relative, relBounds.left, relBounds.top)
             .apply();
 
@@ -204,7 +204,7 @@
             .setLayer(newParentSurface, INT32_MAX - 1)
             .show(newParentSurface)
             .setPosition(newParentSurface, newParentBounds.left, newParentBounds.top)
-            .reparent(childNewClient, newParentSurface->getHandle())
+            .reparent(childNewClient, newParentSurface)
             .apply();
     {
         mCapture = screenshot();
@@ -238,7 +238,7 @@
     }
 
     Transaction()
-            .deferTransactionUntil_legacy(childNewClient, mMainSurface->getHandle(),
+            .deferTransactionUntil_legacy(childNewClient, mMainSurface,
                                           mMainSurface->getSurface()->getNextFrameNumber())
             .apply();
     Transaction().detachChildren(mMainSurface).apply();
@@ -290,7 +290,7 @@
     Transaction().detachChildren(mMainSurface).apply();
     Transaction()
             .setCrop_legacy(childNewClient, {0, 0, childBounds.width(), childBounds.height()})
-            .deferTransactionUntil_legacy(childNewClient, mMainSurface->getHandle(),
+            .deferTransactionUntil_legacy(childNewClient, mMainSurface,
                                           mMainSurface->getSurface()->getNextFrameNumber())
             .apply();
 
@@ -352,7 +352,7 @@
         mCapture->expectColor(mMainSurfaceBounds, Color::BLACK);
     }
 
-    Transaction().reparent(mMainSurface, mBlackBgSurface->getHandle()).apply();
+    Transaction().reparent(mMainSurface, mBlackBgSurface).apply();
     {
         mCapture = screenshot();
         mCapture->expectBorder(childBounds, mMainSurfaceColor);
diff --git a/services/surfaceflinger/tests/LayerRenderTypeTransaction_test.cpp b/services/surfaceflinger/tests/LayerRenderTypeTransaction_test.cpp
index 83e5060..4947289 100644
--- a/services/surfaceflinger/tests/LayerRenderTypeTransaction_test.cpp
+++ b/services/surfaceflinger/tests/LayerRenderTypeTransaction_test.cpp
@@ -211,16 +211,13 @@
 
     switch (layerType) {
         case ISurfaceComposerClient::eFXSurfaceBufferQueue:
-            Transaction()
-                    .setPosition(layerG, 16, 16)
-                    .setRelativeLayer(layerG, layerR->getHandle(), 1)
-                    .apply();
+            Transaction().setPosition(layerG, 16, 16).setRelativeLayer(layerG, layerR, 1).apply();
             break;
         case ISurfaceComposerClient::eFXSurfaceBufferState:
             Transaction()
                     .setFrame(layerR, Rect(0, 0, 32, 32))
                     .setFrame(layerG, Rect(16, 16, 48, 48))
-                    .setRelativeLayer(layerG, layerR->getHandle(), 1)
+                    .setRelativeLayer(layerG, layerR, 1)
                     .apply();
             break;
         default:
@@ -233,7 +230,7 @@
         shot->expectColor(Rect(16, 16, 48, 48), Color::GREEN);
     }
 
-    Transaction().setRelativeLayer(layerG, layerR->getHandle(), -1).apply();
+    Transaction().setRelativeLayer(layerG, layerR, -1).apply();
     {
         SCOPED_TRACE("layerG below");
         auto shot = getScreenCapture();
@@ -266,7 +263,7 @@
         case ISurfaceComposerClient::eFXSurfaceBufferQueue:
             Transaction()
                     .setPosition(layerG, 8, 8)
-                    .setRelativeLayer(layerG, layerR->getHandle(), 3)
+                    .setRelativeLayer(layerG, layerR, 3)
                     .setPosition(layerB, 16, 16)
                     .setLayer(layerB, mLayerZBase + 2)
                     .apply();
@@ -275,7 +272,7 @@
             Transaction()
                     .setFrame(layerR, Rect(0, 0, 32, 32))
                     .setFrame(layerG, Rect(8, 8, 40, 40))
-                    .setRelativeLayer(layerG, layerR->getHandle(), 3)
+                    .setRelativeLayer(layerG, layerR, 3)
                     .setFrame(layerB, Rect(16, 16, 48, 48))
                     .setLayer(layerB, mLayerZBase + 2)
                     .apply();
@@ -303,7 +300,7 @@
     }
 
     // layerR = 4, layerG = layerR - 3, layerB = 2
-    Transaction().setRelativeLayer(layerG, layerR->getHandle(), -3).apply();
+    Transaction().setRelativeLayer(layerG, layerR, -3).apply();
     {
         SCOPED_TRACE("layerB < (layerG < layerR)");
         auto shot = getScreenCapture();
@@ -810,7 +807,7 @@
     // channel) should be less than one
     const uint8_t tolerance = 1;
     Transaction()
-            .reparent(colorLayer, parentLayer->getHandle())
+            .reparent(colorLayer, parentLayer)
             .setColor(colorLayer, color)
             .setAlpha(parentLayer, alpha)
             .setLayer(parentLayer, mLayerZBase + 1)
@@ -1225,7 +1222,7 @@
             child = createLayer("test", 32, 32, ISurfaceComposerClient::eFXSurfaceBufferState));
     ASSERT_NO_FATAL_FAILURE(fillBufferStateLayerColor(child, Color::BLUE, 10, 10));
 
-    Transaction().reparent(child, parent->getHandle()).apply();
+    Transaction().reparent(child, parent).apply();
 
     // A layer will default to the frame of its parent
     auto shot = getScreenCapture();
@@ -1242,7 +1239,7 @@
             child = createLayer("test", 32, 32, ISurfaceComposerClient::eFXSurfaceBufferState));
     ASSERT_NO_FATAL_FAILURE(fillBufferStateLayerColor(child, Color::BLUE, 10, 10));
 
-    Transaction().reparent(child, parent->getHandle()).apply();
+    Transaction().reparent(child, parent).apply();
 
     // A layer will default to the frame of its parent
     auto shot = getScreenCapture();
@@ -1272,7 +1269,7 @@
             parent = createLayer("test", 32, 32, ISurfaceComposerClient::eFXSurfaceBufferState));
     ASSERT_NO_FATAL_FAILURE(
             child = createLayer("test", 32, 32, ISurfaceComposerClient::eFXSurfaceBufferState));
-    Transaction().reparent(child, parent->getHandle()).apply();
+    Transaction().reparent(child, parent).apply();
 
     ASSERT_NO_FATAL_FAILURE(fillBufferStateLayerColor(parent, Color::RED, 32, 32));
     Transaction().setFrame(parent, Rect(0, 0, 32, 32)).apply();
diff --git a/services/surfaceflinger/tests/LayerTransaction_test.cpp b/services/surfaceflinger/tests/LayerTransaction_test.cpp
index 8d715e1..ef992d6 100644
--- a/services/surfaceflinger/tests/LayerTransaction_test.cpp
+++ b/services/surfaceflinger/tests/LayerTransaction_test.cpp
@@ -50,7 +50,7 @@
     sp<SurfaceControl> layer;
     ASSERT_NO_FATAL_FAILURE(layer = createLayer("test", 32, 32));
     ASSERT_NO_FATAL_FAILURE(fillBufferQueueLayerColor(layer, Color::RED, 32, 32));
-    Transaction().reparent(layer, layer->getHandle()).apply();
+    Transaction().reparent(layer, layer).apply();
 
     {
         // We expect the transaction to be silently dropped, but for SurfaceFlinger
diff --git a/services/surfaceflinger/tests/LayerTypeAndRenderTypeTransaction_test.cpp b/services/surfaceflinger/tests/LayerTypeAndRenderTypeTransaction_test.cpp
index 7d4314f..c57ad43 100644
--- a/services/surfaceflinger/tests/LayerTypeAndRenderTypeTransaction_test.cpp
+++ b/services/surfaceflinger/tests/LayerTypeAndRenderTypeTransaction_test.cpp
@@ -87,10 +87,7 @@
     ASSERT_NO_FATAL_FAILURE(layerG = createLayer("test G", 32, 32));
     ASSERT_NO_FATAL_FAILURE(fillLayerColor(layerG, Color::GREEN, 32, 32));
 
-    Transaction()
-            .setPosition(layerG, 16, 16)
-            .setRelativeLayer(layerG, layerR->getHandle(), 1)
-            .apply();
+    Transaction().setPosition(layerG, 16, 16).setRelativeLayer(layerG, layerR, 1).apply();
 
     Transaction().reparent(layerG, nullptr).apply();
 
@@ -154,10 +151,7 @@
     ASSERT_NO_FATAL_FAILURE(layerG = createLayer("test G", 32, 32));
     ASSERT_NO_FATAL_FAILURE(fillLayerColor(layerG, Color::GREEN, 32, 32));
 
-    Transaction()
-            .reparent(layerR, parent->getHandle())
-            .reparent(layerG, parent->getHandle())
-            .apply();
+    Transaction().reparent(layerR, parent).reparent(layerG, parent).apply();
     Transaction().setLayer(layerR, -1).setLayer(layerG, -2).apply();
     {
         SCOPED_TRACE("layerR");
@@ -241,7 +235,7 @@
     auto transaction = Transaction()
                                .setCornerRadius(parent, cornerRadius)
                                .setCrop_legacy(parent, Rect(0, 0, size, size))
-                               .reparent(child, parent->getHandle())
+                               .reparent(child, parent)
                                .setPosition(child, 0, size)
                                // Rotate by half PI
                                .setMatrix(child, 0.0f, -1.0f, 1.0f, 0.0f);
@@ -283,14 +277,14 @@
         Transaction()
                 .setCornerRadius(parent, cornerRadius)
                 .setCrop_legacy(parent, Rect(0, 0, size, size))
-                .reparent(child, parent->getHandle())
+                .reparent(child, parent)
                 .setPosition(child, 0, size / 2)
                 .apply();
     } else {
         Transaction()
                 .setCornerRadius(parent, cornerRadius)
                 .setFrame(parent, Rect(0, 0, size, size))
-                .reparent(child, parent->getHandle())
+                .reparent(child, parent)
                 .setFrame(child, Rect(0, size / 2, size, size))
                 .apply();
     }
diff --git a/services/surfaceflinger/tests/LayerTypeTransaction_test.cpp b/services/surfaceflinger/tests/LayerTypeTransaction_test.cpp
index ab74c50..f8a0bc1 100644
--- a/services/surfaceflinger/tests/LayerTypeTransaction_test.cpp
+++ b/services/surfaceflinger/tests/LayerTypeTransaction_test.cpp
@@ -54,10 +54,10 @@
     ASSERT_NO_FATAL_FAILURE(layerB = createLayer("test B", 32, 32));
     ASSERT_NO_FATAL_FAILURE(fillLayerColor(layerB, Color::BLUE, 32, 32));
 
-    Transaction().reparent(layerB, parent->getHandle()).apply();
+    Transaction().reparent(layerB, parent).apply();
 
     // layerR = mLayerZBase, layerG = layerR - 1, layerB = -2
-    Transaction().setRelativeLayer(layerG, layerR->getHandle(), -1).setLayer(layerB, -2).apply();
+    Transaction().setRelativeLayer(layerG, layerR, -1).setLayer(layerB, -2).apply();
 
     std::unique_ptr<ScreenCapture> screenshot;
     // only layerB is in this range
@@ -88,10 +88,7 @@
             .setCrop_legacy(childLayer, Rect(0, 0, 20, 30))
             .apply();
 
-    Transaction()
-            .setRelativeLayer(childLayer, parent->getHandle(), -1)
-            .setLayer(childLayer, 1)
-            .apply();
+    Transaction().setRelativeLayer(childLayer, parent, -1).setLayer(childLayer, 1).apply();
 
     {
         SCOPED_TRACE("setLayer above");
@@ -101,10 +98,7 @@
         screenshot->expectColor(Rect(0, 0, 20, 30), Color::RED);
     }
 
-    Transaction()
-            .setLayer(childLayer, 1)
-            .setRelativeLayer(childLayer, parent->getHandle(), -1)
-            .apply();
+    Transaction().setLayer(childLayer, 1).setRelativeLayer(childLayer, parent, -1).apply();
 
     {
         SCOPED_TRACE("setRelative below");
@@ -141,7 +135,7 @@
             .setLayer(relativeParent, mLayerZBase)
             .apply();
 
-    Transaction().setRelativeLayer(childLayer, relativeParent->getHandle(), 1).apply();
+    Transaction().setRelativeLayer(childLayer, relativeParent, 1).apply();
 
     {
         SCOPED_TRACE("setLayer above");
diff --git a/services/surfaceflinger/tests/LayerUpdate_test.cpp b/services/surfaceflinger/tests/LayerUpdate_test.cpp
index c56d473..38da0b1 100644
--- a/services/surfaceflinger/tests/LayerUpdate_test.cpp
+++ b/services/surfaceflinger/tests/LayerUpdate_test.cpp
@@ -173,13 +173,13 @@
     // set up two deferred transactions on different frames
     asTransaction([&](Transaction& t) {
         t.setAlpha(mFGSurfaceControl, 0.75);
-        t.deferTransactionUntil_legacy(mFGSurfaceControl, mSyncSurfaceControl->getHandle(),
+        t.deferTransactionUntil_legacy(mFGSurfaceControl, mSyncSurfaceControl,
                                        mSyncSurfaceControl->getSurface()->getNextFrameNumber());
     });
 
     asTransaction([&](Transaction& t) {
         t.setPosition(mFGSurfaceControl, 128, 128);
-        t.deferTransactionUntil_legacy(mFGSurfaceControl, mSyncSurfaceControl->getHandle(),
+        t.deferTransactionUntil_legacy(mFGSurfaceControl, mSyncSurfaceControl,
                                        mSyncSurfaceControl->getSurface()->getNextFrameNumber() + 1);
     });
 
@@ -480,9 +480,8 @@
         mCapture->expectFGColor(84, 84);
     }
 
-    asTransaction([&](Transaction& t) {
-        t.reparentChildren(mFGSurfaceControl, mBGSurfaceControl->getHandle());
-    });
+    asTransaction(
+            [&](Transaction& t) { t.reparentChildren(mFGSurfaceControl, mBGSurfaceControl); });
 
     {
         mCapture = screenshot();
@@ -516,7 +515,7 @@
         mCapture->expectFGColor(64, 64);
     }
 
-    asTransaction([&](Transaction& t) { t.reparent(mGrandChild, mFGSurfaceControl->getHandle()); });
+    asTransaction([&](Transaction& t) { t.reparent(mGrandChild, mFGSurfaceControl); });
 
     {
         SCOPED_TRACE("After reparenting grandchild");
@@ -531,9 +530,7 @@
     TransactionUtils::fillSurfaceRGBA8(mGrandChild, 111, 111, 111);
 
     // draw grand child behind the foreground surface
-    asTransaction([&](Transaction& t) {
-        t.setRelativeLayer(mGrandChild, mFGSurfaceControl->getHandle(), -1);
-    });
+    asTransaction([&](Transaction& t) { t.setRelativeLayer(mGrandChild, mFGSurfaceControl, -1); });
 
     {
         SCOPED_TRACE("Child visible");
@@ -543,7 +540,7 @@
 
     asTransaction([&](Transaction& t) {
         t.reparent(mChild, nullptr);
-        t.reparentChildren(mChild, mFGSurfaceControl->getHandle());
+        t.reparentChildren(mChild, mFGSurfaceControl);
     });
 
     {
@@ -739,7 +736,7 @@
 
     // Show the child layer in a deferred transaction
     asTransaction([&](Transaction& t) {
-        t.deferTransactionUntil_legacy(mChild, mFGSurfaceControl->getHandle(),
+        t.deferTransactionUntil_legacy(mChild, mFGSurfaceControl,
                                        mFGSurfaceControl->getSurface()->getNextFrameNumber());
         t.show(mChild);
     });
@@ -776,7 +773,7 @@
         mCapture->expectFGColor(84, 84);
     }
 
-    asTransaction([&](Transaction& t) { t.reparent(mChild, mBGSurfaceControl->getHandle()); });
+    asTransaction([&](Transaction& t) { t.reparent(mChild, mBGSurfaceControl); });
 
     {
         mCapture = screenshot();
@@ -838,7 +835,7 @@
         mCapture->checkPixel(10, 10, 63, 195, 63);
     }
 
-    asTransaction([&](Transaction& t) { t.reparent(newSurface, mFGSurfaceControl->getHandle()); });
+    asTransaction([&](Transaction& t) { t.reparent(newSurface, mFGSurfaceControl); });
 
     {
         mCapture = screenshot();
@@ -869,7 +866,7 @@
 
     Transaction t;
     t.setLayer(relative, INT32_MAX)
-            .setRelativeLayer(mChild, relative->getHandle(), 1)
+            .setRelativeLayer(mChild, relative, 1)
             .setPosition(mFGSurfaceControl, 0, 0)
             .apply(true);
 
diff --git a/services/surfaceflinger/tests/MirrorLayer_test.cpp b/services/surfaceflinger/tests/MirrorLayer_test.cpp
index b49bd54..16826c1 100644
--- a/services/surfaceflinger/tests/MirrorLayer_test.cpp
+++ b/services/surfaceflinger/tests/MirrorLayer_test.cpp
@@ -68,7 +68,7 @@
 
     // Add mirrorLayer as child of mParentLayer so it's shown on the display
     Transaction()
-            .reparent(mirrorLayer, mParentLayer->getHandle())
+            .reparent(mirrorLayer, mParentLayer)
             .setPosition(mirrorLayer, 500, 500)
             .show(mirrorLayer)
             .apply();
@@ -127,7 +127,7 @@
     }
 
     // Add grandchild layer to offscreen layer
-    Transaction().reparent(grandchild, mChildLayer->getHandle()).apply();
+    Transaction().reparent(grandchild, mChildLayer).apply();
     {
         SCOPED_TRACE("Added Grandchild Layer");
         auto shot = screenshot();
@@ -138,7 +138,7 @@
     }
 
     // Add child layer
-    Transaction().reparent(mChildLayer, mParentLayer->getHandle()).apply();
+    Transaction().reparent(mChildLayer, mParentLayer).apply();
     {
         SCOPED_TRACE("Added Child Layer");
         auto shot = screenshot();
@@ -157,7 +157,7 @@
 
     sp<SurfaceControl> mirrorLayer = mClient->mirrorSurface(mChildLayer.get());
     Transaction()
-            .reparent(mirrorLayer, mParentLayer->getHandle())
+            .reparent(mirrorLayer, mParentLayer)
             .setPosition(mirrorLayer, 500, 500)
             .show(mirrorLayer)
             .apply();
diff --git a/services/surfaceflinger/tests/RelativeZ_test.cpp b/services/surfaceflinger/tests/RelativeZ_test.cpp
index 3e0b3c6..fde6e6e 100644
--- a/services/surfaceflinger/tests/RelativeZ_test.cpp
+++ b/services/surfaceflinger/tests/RelativeZ_test.cpp
@@ -70,10 +70,7 @@
     sp<SurfaceControl> childLayer =
             createColorLayer("Child layer", Color::BLUE, mBackgroundLayer.get());
 
-    Transaction{}
-            .setRelativeLayer(childLayer, mForegroundLayer->getHandle(), 1)
-            .show(childLayer)
-            .apply();
+    Transaction{}.setRelativeLayer(childLayer, mForegroundLayer, 1).show(childLayer).apply();
 
     {
         // The childLayer should be in front of the FG control.
@@ -88,7 +85,7 @@
     // Background layer (RED)
     //   Child layer (WHITE)
     // Foregroud layer (GREEN)
-    Transaction{}.reparent(childLayer, mBackgroundLayer->getHandle()).apply();
+    Transaction{}.reparent(childLayer, mBackgroundLayer).apply();
 
     {
         // The relative z info for child layer should be reset, leaving FG control on top.
@@ -118,7 +115,7 @@
             createColorLayer("child level 3", Color::GREEN, childLevel2a.get());
 
     Transaction{}
-            .setRelativeLayer(childLevel3, childLevel2b->getHandle(), 1)
+            .setRelativeLayer(childLevel3, childLevel2b, 1)
             .show(childLevel2a)
             .show(childLevel2b)
             .show(childLevel3)
@@ -140,7 +137,7 @@
     //     child level 2 back (BLUE)
     //       child level 3 (GREEN) (relative to child level 2b)
     //     child level 2 front (BLACK)
-    Transaction{}.reparent(childLevel1, mForegroundLayer->getHandle()).apply();
+    Transaction{}.reparent(childLevel1, mForegroundLayer).apply();
 
     {
         // Nothing should change at this point since relative z info was preserved.
@@ -162,7 +159,7 @@
             createColorLayer("Relative layer", Color::WHITE, mForegroundLayer.get());
 
     Transaction{}
-            .setRelativeLayer(childLayer, relativeToLayer->getHandle(), 1)
+            .setRelativeLayer(childLayer, relativeToLayer, 1)
             .show(childLayer)
             .show(relativeToLayer)
             .apply();
@@ -199,7 +196,7 @@
     // Background layer (RED)
     // Foregroud layer (GREEN)
     //   Child layer (BLUE)
-    Transaction{}.reparent(childLayer, mForegroundLayer->getHandle()).apply();
+    Transaction{}.reparent(childLayer, mForegroundLayer).apply();
 
     {
         // The relative z info for child layer should be reset, leaving the child layer on top.
@@ -230,7 +227,7 @@
             createColorLayer("child level 2b", Color::BLACK, childLevel1b.get());
 
     Transaction{}
-            .setRelativeLayer(childLevel1a, childLevel2b->getHandle(), 1)
+            .setRelativeLayer(childLevel1a, childLevel2b, 1)
             .show(childLevel1a)
             .show(childLevel1b)
             .show(childLevel2a)
@@ -250,7 +247,7 @@
 
     // // Background layer (RED)
     // // Foregroud layer (GREEN)
-    Transaction{}.reparent(childLevel1a, childLevel2a->getHandle()).apply();
+    Transaction{}.reparent(childLevel1a, childLevel2a).apply();
 
     {
         // The childLevel1a and childLevel1b are no longer on screen
@@ -264,7 +261,7 @@
     //     child level 2a (BLUE)
     //       child level 1a (testLayerColor) (relative to child level 2b)
     //     child level 2b (BLACK)
-    Transaction{}.reparent(childLevel1b, mForegroundLayer->getHandle()).apply();
+    Transaction{}.reparent(childLevel1b, mForegroundLayer).apply();
 
     {
         // Nothing should change at this point since relative z info was preserved.
diff --git a/services/surfaceflinger/tests/ScreenCapture_test.cpp b/services/surfaceflinger/tests/ScreenCapture_test.cpp
index 3ab2ad1..e173996 100644
--- a/services/surfaceflinger/tests/ScreenCapture_test.cpp
+++ b/services/surfaceflinger/tests/ScreenCapture_test.cpp
@@ -239,7 +239,7 @@
     SurfaceComposerClient::Transaction()
             .show(child)
             // Set relative layer above fg layer so should be shown above when computing all layers.
-            .setRelativeLayer(relative, mFGSurfaceControl->getHandle(), 1)
+            .setRelativeLayer(relative, mFGSurfaceControl, 1)
             .show(relative)
             .apply(true);
 
@@ -264,7 +264,7 @@
             // Set relative layer below fg layer but relative to child layer so it should be shown
             // above child layer.
             .setLayer(relative, -1)
-            .setRelativeLayer(relative, child->getHandle(), 1)
+            .setRelativeLayer(relative, child, 1)
             .show(relative)
             .apply(true);
 
@@ -707,7 +707,7 @@
             .setLayer(layerWithFakeUid, INT32_MAX)
             .setPosition(layerWithFakeUid, 128, 128)
             // reparent a layer that was created with a different uid to the new layer.
-            .reparent(layer, layerWithFakeUid->getHandle())
+            .reparent(layer, layerWithFakeUid)
             .apply();
 
     // Screenshot from the fakeUid caller with the uid requested allows the layer
diff --git a/services/surfaceflinger/tests/SurfaceInterceptor_test.cpp b/services/surfaceflinger/tests/SurfaceInterceptor_test.cpp
index 8570032..104d919 100644
--- a/services/surfaceflinger/tests/SurfaceInterceptor_test.cpp
+++ b/services/surfaceflinger/tests/SurfaceInterceptor_test.cpp
@@ -397,16 +397,15 @@
 }
 
 void SurfaceInterceptorTest::deferredTransactionUpdate(Transaction& t) {
-    t.deferTransactionUntil_legacy(mBGSurfaceControl, mBGSurfaceControl->getHandle(),
-                                   DEFERRED_UPDATE);
+    t.deferTransactionUntil_legacy(mBGSurfaceControl, mBGSurfaceControl, DEFERRED_UPDATE);
 }
 
 void SurfaceInterceptorTest::reparentUpdate(Transaction& t) {
-    t.reparent(mBGSurfaceControl, mFGSurfaceControl->getHandle());
+    t.reparent(mBGSurfaceControl, mFGSurfaceControl);
 }
 
 void SurfaceInterceptorTest::relativeParentUpdate(Transaction& t) {
-    t.setRelativeLayer(mBGSurfaceControl, mFGSurfaceControl->getHandle(), RELATIVE_Z);
+    t.setRelativeLayer(mBGSurfaceControl, mFGSurfaceControl, RELATIVE_Z);
 }
 
 void SurfaceInterceptorTest::detachChildrenUpdate(Transaction& t) {
@@ -414,7 +413,7 @@
 }
 
 void SurfaceInterceptorTest::reparentChildrenUpdate(Transaction& t) {
-    t.reparentChildren(mBGSurfaceControl, mFGSurfaceControl->getHandle());
+    t.reparentChildren(mBGSurfaceControl, mFGSurfaceControl);
 }
 
 void SurfaceInterceptorTest::shadowRadiusUpdate(Transaction& t) {
diff --git a/services/surfaceflinger/tests/fakehwc/SFFakeHwc_test.cpp b/services/surfaceflinger/tests/fakehwc/SFFakeHwc_test.cpp
index 87fc08a..07c558f 100644
--- a/services/surfaceflinger/tests/fakehwc/SFFakeHwc_test.cpp
+++ b/services/surfaceflinger/tests/fakehwc/SFFakeHwc_test.cpp
@@ -1322,7 +1322,7 @@
         {
             TransactionScope ts(*sFakeComposer);
             ts.setAlpha(mFGSurfaceControl, 0.75);
-            ts.deferTransactionUntil_legacy(mFGSurfaceControl, syncSurfaceControl->getHandle(),
+            ts.deferTransactionUntil_legacy(mFGSurfaceControl, syncSurfaceControl,
                                             syncSurfaceControl->getSurface()->getNextFrameNumber());
         }
         EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
@@ -1330,7 +1330,7 @@
         {
             TransactionScope ts(*sFakeComposer);
             ts.setPosition(mFGSurfaceControl, 128, 128);
-            ts.deferTransactionUntil_legacy(mFGSurfaceControl, syncSurfaceControl->getHandle(),
+            ts.deferTransactionUntil_legacy(mFGSurfaceControl, syncSurfaceControl,
                                             syncSurfaceControl->getSurface()->getNextFrameNumber() +
                                                     1);
         }
@@ -1376,7 +1376,7 @@
             TransactionScope ts(*sFakeComposer);
             ts.setPosition(relativeSurfaceControl, 64, 64);
             ts.show(relativeSurfaceControl);
-            ts.setRelativeLayer(relativeSurfaceControl, mFGSurfaceControl->getHandle(), 1);
+            ts.setRelativeLayer(relativeSurfaceControl, mFGSurfaceControl, 1);
         }
         auto referenceFrame = mBaseFrame;
         // NOTE: All three layers will be visible as the surfaces are
@@ -1606,7 +1606,7 @@
 
         {
             TransactionScope ts(*Base::sFakeComposer);
-            ts.reparentChildren(Base::mFGSurfaceControl, Base::mBGSurfaceControl->getHandle());
+            ts.reparentChildren(Base::mFGSurfaceControl, Base::mBGSurfaceControl);
         }
 
         auto referenceFrame2 = referenceFrame;
@@ -1761,7 +1761,7 @@
         // Show the child layer in a deferred transaction
         {
             TransactionScope ts(*Base::sFakeComposer);
-            ts.deferTransactionUntil_legacy(mChild, Base::mFGSurfaceControl->getHandle(),
+            ts.deferTransactionUntil_legacy(mChild, Base::mFGSurfaceControl,
                                             Base::mFGSurfaceControl->getSurface()
                                                     ->getNextFrameNumber());
             ts.show(mChild);
diff --git a/services/surfaceflinger/tests/unittests/Android.bp b/services/surfaceflinger/tests/unittests/Android.bp
index cf3a4c2..9655cf3 100644
--- a/services/surfaceflinger/tests/unittests/Android.bp
+++ b/services/surfaceflinger/tests/unittests/Android.bp
@@ -39,6 +39,7 @@
         "CompositionTest.cpp",
         "DispSyncSourceTest.cpp",
         "DisplayIdentificationTest.cpp",
+        "DisplayIdGeneratorTest.cpp",
         "DisplayTransactionTest.cpp",
         "EventThreadTest.cpp",
         "FrameTimelineTest.cpp",
diff --git a/services/surfaceflinger/tests/unittests/DisplayIdGeneratorTest.cpp b/services/surfaceflinger/tests/unittests/DisplayIdGeneratorTest.cpp
new file mode 100644
index 0000000..be7609a
--- /dev/null
+++ b/services/surfaceflinger/tests/unittests/DisplayIdGeneratorTest.cpp
@@ -0,0 +1,82 @@
+/*
+ * Copyright 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <gtest/gtest.h>
+
+#include <vector>
+
+#include <ui/DisplayId.h>
+#include "DisplayIdGenerator.h"
+
+namespace android {
+
+template <typename T>
+void testNextId(DisplayIdGenerator<T>& generator) {
+    constexpr int kNumIds = 5;
+    std::vector<T> ids;
+    for (int i = 0; i < kNumIds; i++) {
+        const auto id = generator.nextId();
+        ASSERT_TRUE(id);
+        ids.push_back(*id);
+    }
+
+    // All IDs should be different.
+    for (size_t i = 0; i < kNumIds; i++) {
+        for (size_t j = i + 1; j < kNumIds; j++) {
+            EXPECT_NE(ids[i], ids[j]);
+        }
+    }
+}
+
+TEST(DisplayIdGeneratorTest, nextIdGpuVirtual) {
+    RandomDisplayIdGenerator<GpuVirtualDisplayId> generator;
+    testNextId(generator);
+}
+
+TEST(DisplayIdGeneratorTest, nextIdHalVirtual) {
+    RandomDisplayIdGenerator<HalVirtualDisplayId> generator;
+    testNextId(generator);
+}
+
+TEST(DisplayIdGeneratorTest, markUnused) {
+    constexpr size_t kMaxIdsCount = 5;
+    RandomDisplayIdGenerator<GpuVirtualDisplayId> generator(kMaxIdsCount);
+
+    const auto id = generator.nextId();
+    EXPECT_TRUE(id);
+
+    for (int i = 1; i < kMaxIdsCount; i++) {
+        EXPECT_TRUE(generator.nextId());
+    }
+
+    EXPECT_FALSE(generator.nextId());
+
+    generator.markUnused(*id);
+    EXPECT_TRUE(generator.nextId());
+}
+
+TEST(DisplayIdGeneratorTest, maxIdsCount) {
+    constexpr size_t kMaxIdsCount = 5;
+    RandomDisplayIdGenerator<GpuVirtualDisplayId> generator(kMaxIdsCount);
+
+    for (int i = 0; i < kMaxIdsCount; i++) {
+        EXPECT_TRUE(generator.nextId());
+    }
+
+    EXPECT_FALSE(generator.nextId());
+}
+
+} // namespace android
diff --git a/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp b/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp
index 5864d02..e055e95 100644
--- a/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp
+++ b/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp
@@ -338,9 +338,9 @@
 struct PhysicalDisplayIdType {};
 
 template <uint64_t displayId>
-using VirtualDisplayIdType = std::integral_constant<uint64_t, displayId>;
+using HalVirtualDisplayIdType = std::integral_constant<uint64_t, displayId>;
 
-struct NoDisplayId {};
+struct GpuVirtualDisplayIdType {};
 
 template <typename>
 struct IsPhysicalDisplayId : std::bool_constant<false> {};
@@ -353,7 +353,7 @@
 
 template <typename PhysicalDisplay>
 struct DisplayIdGetter<PhysicalDisplayIdType<PhysicalDisplay>> {
-    static std::optional<PhysicalDisplayId> get() {
+    static PhysicalDisplayId get() {
         if (!PhysicalDisplay::HAS_IDENTIFICATION_DATA) {
             return PhysicalDisplayId::fromPort(static_cast<bool>(PhysicalDisplay::PRIMARY)
                                                        ? LEGACY_DISPLAY_TYPE_PRIMARY
@@ -363,19 +363,18 @@
         const auto info =
                 parseDisplayIdentificationData(PhysicalDisplay::PORT,
                                                PhysicalDisplay::GET_IDENTIFICATION_DATA());
-        return info ? std::make_optional(info->id) : std::nullopt;
+        return info ? info->id : PhysicalDisplayId::fromPort(PhysicalDisplay::PORT);
     }
 };
 
 template <uint64_t displayId>
-struct DisplayIdGetter<VirtualDisplayIdType<displayId>> {
-    // TODO(b/160679868) Use VirtualDisplayId
-    static std::optional<PhysicalDisplayId> get() { return PhysicalDisplayId{displayId}; }
+struct DisplayIdGetter<HalVirtualDisplayIdType<displayId>> {
+    static HalVirtualDisplayId get() { return HalVirtualDisplayId(displayId); }
 };
 
 template <>
-struct DisplayIdGetter<NoDisplayId> {
-    static std::optional<DisplayId> get() { return {}; }
+struct DisplayIdGetter<GpuVirtualDisplayIdType> {
+    static GpuVirtualDisplayId get() { return GpuVirtualDisplayId(0); }
 };
 
 template <typename>
@@ -396,7 +395,7 @@
 constexpr HWDisplayId HWC_VIRTUAL_DISPLAY_HWC_DISPLAY_ID = 1010;
 
 template <uint64_t displayId>
-struct HwcDisplayIdGetter<VirtualDisplayIdType<displayId>> {
+struct HwcDisplayIdGetter<HalVirtualDisplayIdType<displayId>> {
     static constexpr std::optional<HWDisplayId> value = HWC_VIRTUAL_DISPLAY_HWC_DISPLAY_ID;
 };
 
@@ -407,8 +406,8 @@
 
 // DisplayIdType can be:
 //     1) PhysicalDisplayIdType<...> for generated ID of physical display backed by HWC.
-//     2) VirtualDisplayIdType<...> for hard-coded ID of virtual display backed by HWC.
-//     3) NoDisplayId for virtual display without HWC backing.
+//     2) HalVirtualDisplayIdType<...> for hard-coded ID of virtual display backed by HWC.
+//     3) GpuVirtualDisplayIdType for virtual display without HWC backing.
 template <typename DisplayIdType, int width, int height, Critical critical, Async async,
           Secure secure, Primary primary, int grallocUsage>
 struct DisplayVariant {
@@ -440,17 +439,36 @@
 
     static auto makeFakeExistingDisplayInjector(DisplayTransactionTest* test) {
         auto ceDisplayArgs = compositionengine::DisplayCreationArgsBuilder();
-        if (auto displayId = DISPLAY_ID::get()) {
+        if (auto displayId = PhysicalDisplayId::tryCast(DISPLAY_ID::get())) {
             ceDisplayArgs.setPhysical({*displayId, DisplayConnectionType::Internal});
         } else {
+            // We turn off the use of HwcVirtualDisplays, to prevent Composition Engine
+            // from calling into HWComposer. This way all virtual displays will get
+            // a GpuVirtualDisplayId, even if we are in the HwcVirtualDisplayVariant.
+            // In this case we later override it by calling display.setDisplayIdForTesting().
             ceDisplayArgs.setUseHwcVirtualDisplays(false);
+
+            GpuVirtualDisplayId desiredDisplayId = GpuVirtualDisplayId::tryCast(DISPLAY_ID::get())
+                                                           .value_or(GpuVirtualDisplayId(0));
+
+            ON_CALL(test->mFlinger.gpuVirtualDisplayIdGenerator(), nextId())
+                    .WillByDefault(Return(desiredDisplayId));
+
+            auto& generator = test->mFlinger.gpuVirtualDisplayIdGenerator();
+            ceDisplayArgs.setGpuVirtualDisplayIdGenerator(generator);
         }
-        ceDisplayArgs.setPixels({WIDTH, HEIGHT}).setPowerAdvisor(&test->mPowerAdvisor).build();
+        ceDisplayArgs.setPixels({WIDTH, HEIGHT}).setPowerAdvisor(&test->mPowerAdvisor);
 
         auto compositionDisplay =
                 compositionengine::impl::createDisplay(test->mFlinger.getCompositionEngine(),
                                                        ceDisplayArgs.build());
 
+        if (HalVirtualDisplayId::tryCast(DISPLAY_ID::get())) {
+            // CompositionEngine has assigned a placeholder GpuVirtualDisplayId and we need to
+            // override it with the correct HalVirtualDisplayId.
+            compositionDisplay->setDisplayIdForTesting(DISPLAY_ID::get());
+        }
+
         auto injector = FakeDisplayDeviceInjector(test->mFlinger, compositionDisplay,
                                                   CONNECTION_TYPE::value, HWC_DISPLAY_ID_OPT::value,
                                                   static_cast<bool>(PRIMARY));
@@ -532,8 +550,8 @@
     // Called by tests to inject a HWC display setup
     static void injectHwcDisplayWithNoDefaultCapabilities(DisplayTransactionTest* test) {
         const auto displayId = DisplayVariant::DISPLAY_ID::get();
-        ASSERT_TRUE(displayId);
-        FakeHwcDisplayInjector(*displayId, HWC_DISPLAY_TYPE,
+        ASSERT_FALSE(GpuVirtualDisplayId::tryCast(displayId));
+        FakeHwcDisplayInjector(displayId, HWC_DISPLAY_TYPE,
                                static_cast<bool>(DisplayVariant::PRIMARY))
                 .setHwcDisplayId(HWC_DISPLAY_ID)
                 .setWidth(DisplayVariant::WIDTH)
@@ -559,7 +577,7 @@
                 ::testing::UnitTest::GetInstance()->current_test_info();
 
         auto ceDisplayArgs = compositionengine::DisplayCreationArgsBuilder()
-                                     .setPhysical({*DisplayVariant::DISPLAY_ID::get(),
+                                     .setPhysical({DisplayVariant::DISPLAY_ID::get(),
                                                    PhysicalDisplay::CONNECTION_TYPE})
                                      .setPixels({DisplayVariant::WIDTH, DisplayVariant::HEIGHT})
                                      .setIsSecure(static_cast<bool>(DisplayVariant::SECURE))
@@ -686,10 +704,11 @@
 
 template <int width, int height, Secure secure>
 struct NonHwcVirtualDisplayVariant
-      : DisplayVariant<NoDisplayId, width, height, Critical::FALSE, Async::TRUE, secure,
+      : DisplayVariant<GpuVirtualDisplayIdType, width, height, Critical::FALSE, Async::TRUE, secure,
                        Primary::FALSE, GRALLOC_USAGE_NONHWC_VIRTUAL_DISPLAY> {
-    using Base = DisplayVariant<NoDisplayId, width, height, Critical::FALSE, Async::TRUE, secure,
-                                Primary::FALSE, GRALLOC_USAGE_NONHWC_VIRTUAL_DISPLAY>;
+    using Base =
+            DisplayVariant<GpuVirtualDisplayIdType, width, height, Critical::FALSE, Async::TRUE,
+                           secure, Primary::FALSE, GRALLOC_USAGE_NONHWC_VIRTUAL_DISPLAY>;
 
     static void injectHwcDisplay(DisplayTransactionTest*) {}
 
@@ -698,12 +717,17 @@
         const ::testing::TestInfo* const test_info =
                 ::testing::UnitTest::GetInstance()->current_test_info();
 
+        ON_CALL(test->mFlinger.gpuVirtualDisplayIdGenerator(), nextId())
+                .WillByDefault(Return(Base::DISPLAY_ID::get()));
+
         auto ceDisplayArgs = compositionengine::DisplayCreationArgsBuilder()
                                      .setPixels({Base::WIDTH, Base::HEIGHT})
                                      .setIsSecure(static_cast<bool>(Base::SECURE))
                                      .setPowerAdvisor(&test->mPowerAdvisor)
                                      .setName(std::string("Injected display for ") +
                                               test_info->test_case_name() + "." + test_info->name())
+                                     .setGpuVirtualDisplayIdGenerator(
+                                             test->mFlinger.gpuVirtualDisplayIdGenerator())
                                      .build();
 
         return compositionengine::impl::createDisplay(test->mFlinger.getCompositionEngine(),
@@ -725,13 +749,13 @@
 
 template <int width, int height, Secure secure>
 struct HwcVirtualDisplayVariant
-      : DisplayVariant<VirtualDisplayIdType<42>, width, height, Critical::FALSE, Async::TRUE,
+      : DisplayVariant<HalVirtualDisplayIdType<42>, width, height, Critical::FALSE, Async::TRUE,
                        secure, Primary::FALSE, GRALLOC_USAGE_HWC_VIRTUAL_DISPLAY>,
         HwcDisplayVariant<HWC_VIRTUAL_DISPLAY_HWC_DISPLAY_ID, DisplayType::VIRTUAL,
-                          DisplayVariant<VirtualDisplayIdType<42>, width, height, Critical::FALSE,
-                                         Async::TRUE, secure, Primary::FALSE,
+                          DisplayVariant<HalVirtualDisplayIdType<42>, width, height,
+                                         Critical::FALSE, Async::TRUE, secure, Primary::FALSE,
                                          GRALLOC_USAGE_HWC_VIRTUAL_DISPLAY>> {
-    using Base = DisplayVariant<VirtualDisplayIdType<42>, width, height, Critical::FALSE,
+    using Base = DisplayVariant<HalVirtualDisplayIdType<42>, width, height, Critical::FALSE,
                                 Async::TRUE, secure, Primary::FALSE, GRALLOC_USAGE_HW_COMPOSER>;
     using Self = HwcVirtualDisplayVariant<width, height, secure>;
 
@@ -740,6 +764,14 @@
         const ::testing::TestInfo* const test_info =
                 ::testing::UnitTest::GetInstance()->current_test_info();
 
+        // In order to prevent compostition engine calling into HWComposer, we
+        // 1. turn off the use of HWC virtual displays,
+        // 2. provide a GpuVirtualDisplayIdGenerator which always returns some fake ID
+        // 3. override the ID by calling setDisplayIdForTesting()
+
+        ON_CALL(test->mFlinger.gpuVirtualDisplayIdGenerator(), nextId())
+                .WillByDefault(Return(GpuVirtualDisplayId(0)));
+
         auto ceDisplayArgs = compositionengine::DisplayCreationArgsBuilder()
                                      .setUseHwcVirtualDisplays(false)
                                      .setPixels({Base::WIDTH, Base::HEIGHT})
@@ -747,6 +779,8 @@
                                      .setPowerAdvisor(&test->mPowerAdvisor)
                                      .setName(std::string("Injected display for ") +
                                               test_info->test_case_name() + "." + test_info->name())
+                                     .setGpuVirtualDisplayIdGenerator(
+                                             test->mFlinger.gpuVirtualDisplayIdGenerator())
                                      .build();
 
         auto compositionDisplay =
@@ -755,8 +789,9 @@
         compositionDisplay->setDisplayIdForTesting(Base::DISPLAY_ID::get());
 
         // Insert display data so that the HWC thinks it created the virtual display.
-        if (const auto displayId = Base::DISPLAY_ID::get()) {
-            test->mFlinger.mutableHwcDisplayData().try_emplace(*displayId);
+        if (const auto displayId = Base::DISPLAY_ID::get();
+            HalVirtualDisplayId::tryCast(displayId)) {
+            test->mFlinger.mutableHwcDisplayData().try_emplace(displayId);
         }
 
         return compositionDisplay;
@@ -1776,13 +1811,11 @@
 
     DisplayDeviceState state;
     if (const auto connectionType = Case::Display::CONNECTION_TYPE::value) {
-        const auto displayId = Case::Display::DISPLAY_ID::get();
+        const auto displayId = PhysicalDisplayId::tryCast(Case::Display::DISPLAY_ID::get());
         ASSERT_TRUE(displayId);
         const auto hwcDisplayId = Case::Display::HWC_DISPLAY_ID_OPT::value;
         ASSERT_TRUE(hwcDisplayId);
-        state.physical = {.id = static_cast<PhysicalDisplayId>(*displayId),
-                          .type = *connectionType,
-                          .hwcDisplayId = *hwcDisplayId};
+        state.physical = {.id = *displayId, .type = *connectionType, .hwcDisplayId = *hwcDisplayId};
     }
 
     state.isSecure = static_cast<bool>(Case::Display::SECURE);
@@ -1954,11 +1987,11 @@
 
     std::optional<DisplayDeviceState::Physical> expectedPhysical;
     if (const auto connectionType = Case::Display::CONNECTION_TYPE::value) {
-        const auto displayId = Case::Display::DISPLAY_ID::get();
+        const auto displayId = PhysicalDisplayId::tryCast(Case::Display::DISPLAY_ID::get());
         ASSERT_TRUE(displayId);
         const auto hwcDisplayId = Case::Display::HWC_DISPLAY_ID_OPT::value;
         ASSERT_TRUE(hwcDisplayId);
-        expectedPhysical = {.id = static_cast<PhysicalDisplayId>(*displayId),
+        expectedPhysical = {.id = *displayId,
                             .type = *connectionType,
                             .hwcDisplayId = *hwcDisplayId};
     }
@@ -1983,9 +2016,9 @@
 
     // SF should have a display token.
     const auto displayId = Case::Display::DISPLAY_ID::get();
-    ASSERT_TRUE(displayId);
-    ASSERT_TRUE(mFlinger.mutablePhysicalDisplayTokens().count(*displayId) == 1);
-    auto& displayToken = mFlinger.mutablePhysicalDisplayTokens()[*displayId];
+    ASSERT_TRUE(PhysicalDisplayId::tryCast(displayId));
+    ASSERT_TRUE(mFlinger.mutablePhysicalDisplayTokens().count(displayId) == 1);
+    auto& displayToken = mFlinger.mutablePhysicalDisplayTokens()[displayId];
 
     verifyDisplayIsConnected<Case>(displayToken);
 }
@@ -2088,8 +2121,8 @@
 
     // SF should not have a display token.
     const auto displayId = Case::Display::DISPLAY_ID::get();
-    ASSERT_TRUE(displayId);
-    ASSERT_TRUE(mFlinger.mutablePhysicalDisplayTokens().count(*displayId) == 0);
+    ASSERT_TRUE(PhysicalDisplayId::tryCast(displayId));
+    ASSERT_TRUE(mFlinger.mutablePhysicalDisplayTokens().count(displayId) == 0);
 
     // The existing token should have been removed
     verifyDisplayIsNotConnected(existing.token());
@@ -2174,8 +2207,8 @@
 
     // SF should not have a display token.
     const auto displayId = Case::Display::DISPLAY_ID::get();
-    ASSERT_TRUE(displayId);
-    ASSERT_TRUE(mFlinger.mutablePhysicalDisplayTokens().count(*displayId) == 0);
+    ASSERT_TRUE(PhysicalDisplayId::tryCast(displayId));
+    ASSERT_TRUE(mFlinger.mutablePhysicalDisplayTokens().count(displayId) == 0);
 }
 
 TEST_F(HandleTransactionLockedTest, processesHotplugDisconnectThenConnectPrimary) {
@@ -2213,9 +2246,9 @@
     // The existing token should have been removed
     verifyDisplayIsNotConnected(existing.token());
     const auto displayId = Case::Display::DISPLAY_ID::get();
-    ASSERT_TRUE(displayId);
-    ASSERT_TRUE(mFlinger.mutablePhysicalDisplayTokens().count(*displayId) == 1);
-    EXPECT_NE(existing.token(), mFlinger.mutablePhysicalDisplayTokens()[*displayId]);
+    ASSERT_TRUE(PhysicalDisplayId::tryCast(displayId));
+    ASSERT_TRUE(mFlinger.mutablePhysicalDisplayTokens().count(displayId) == 1);
+    EXPECT_NE(existing.token(), mFlinger.mutablePhysicalDisplayTokens()[displayId]);
 
     // A new display should be connected in its place
 
@@ -2349,8 +2382,8 @@
 
     // A virtual display is set up but is removed from the current state.
     const auto displayId = Case::Display::DISPLAY_ID::get();
-    ASSERT_TRUE(displayId);
-    mFlinger.mutableHwcDisplayData().try_emplace(*displayId);
+    ASSERT_TRUE(HalVirtualDisplayId::tryCast(displayId));
+    mFlinger.mutableHwcDisplayData().try_emplace(displayId);
     Case::Display::injectHwcDisplay(this);
     auto existing = Case::Display::makeFakeExistingDisplayInjector(this);
     existing.inject();
@@ -3485,8 +3518,8 @@
 
     // Insert display data so that the HWC thinks it created the virtual display.
     const auto displayId = Case::Display::DISPLAY_ID::get();
-    ASSERT_TRUE(displayId);
-    mFlinger.mutableHwcDisplayData().try_emplace(*displayId);
+    ASSERT_TRUE(HalVirtualDisplayId::tryCast(displayId));
+    mFlinger.mutableHwcDisplayData().try_emplace(displayId);
 
     // A virtual display device is set up
     Case::Display::injectHwcDisplay(this);
diff --git a/services/surfaceflinger/tests/unittests/FrameTimelineTest.cpp b/services/surfaceflinger/tests/unittests/FrameTimelineTest.cpp
index 85d2834..617f95a 100644
--- a/services/surfaceflinger/tests/unittests/FrameTimelineTest.cpp
+++ b/services/surfaceflinger/tests/unittests/FrameTimelineTest.cpp
@@ -217,4 +217,20 @@
               true);
 }
 
+TEST_F(FrameTimelineTest, surfaceFrameEndTimeAcquireFenceAfterQueue) {
+    auto surfaceFrame =
+            mFrameTimeline->createSurfaceFrameForToken("acquireFenceAfterQueue", std::nullopt);
+    surfaceFrame->setActualQueueTime(123);
+    surfaceFrame->setAcquireFenceTime(456);
+    EXPECT_EQ(surfaceFrame->getActuals().endTime, 456);
+}
+
+TEST_F(FrameTimelineTest, surfaceFrameEndTimeAcquireFenceBeforeQueue) {
+    auto surfaceFrame =
+            mFrameTimeline->createSurfaceFrameForToken("acquireFenceAfterQueue", std::nullopt);
+    surfaceFrame->setActualQueueTime(456);
+    surfaceFrame->setAcquireFenceTime(123);
+    EXPECT_EQ(surfaceFrame->getActuals().endTime, 456);
+}
+
 } // namespace android::frametimeline
diff --git a/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h b/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
index 8c12e94..9ff8f4e 100644
--- a/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
+++ b/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
@@ -40,6 +40,7 @@
 #include "SurfaceInterceptor.h"
 #include "TestableScheduler.h"
 #include "mock/DisplayHardware/MockDisplay.h"
+#include "mock/MockDisplayIdGenerator.h"
 
 namespace android {
 
@@ -83,8 +84,8 @@
         return nullptr;
     }
 
-    sp<SurfaceInterceptor> createSurfaceInterceptor(SurfaceFlinger* flinger) override {
-        return new android::impl::SurfaceInterceptor(flinger);
+    sp<SurfaceInterceptor> createSurfaceInterceptor() override {
+        return new android::impl::SurfaceInterceptor();
     }
 
     sp<StartPropertySetThread> createStartPropertySetThread(bool timestampPropertyValue) override {
@@ -171,6 +172,9 @@
 
     SurfaceFlinger* flinger() { return mFlinger.get(); }
     TestableScheduler* scheduler() { return mScheduler; }
+    mock::DisplayIdGenerator<GpuVirtualDisplayId>& gpuVirtualDisplayIdGenerator() {
+        return mGpuVirtualDisplayIdGenerator;
+    }
 
     // Extend this as needed for accessing SurfaceFlinger private (and public)
     // functions.
@@ -463,7 +467,8 @@
         static constexpr hal::HWConfigId DEFAULT_ACTIVE_CONFIG = 0;
         static constexpr hal::PowerMode DEFAULT_POWER_MODE = hal::PowerMode::ON;
 
-        FakeHwcDisplayInjector(DisplayId displayId, hal::DisplayType hwcDisplayType, bool isPrimary)
+        FakeHwcDisplayInjector(HalDisplayId displayId, hal::DisplayType hwcDisplayType,
+                               bool isPrimary)
               : mDisplayId(displayId), mHwcDisplayType(hwcDisplayType), mIsPrimary(isPrimary) {}
 
         auto& setHwcDisplayId(hal::HWDisplayId displayId) {
@@ -536,14 +541,16 @@
             flinger->mutableHwcDisplayData()[mDisplayId].hwcDisplay = std::move(display);
 
             if (mHwcDisplayType == hal::DisplayType::PHYSICAL) {
-                flinger->mutableHwcPhysicalDisplayIdMap().emplace(mHwcDisplayId, mDisplayId);
+                const auto physicalId = PhysicalDisplayId::tryCast(mDisplayId);
+                LOG_ALWAYS_FATAL_IF(!physicalId);
+                flinger->mutableHwcPhysicalDisplayIdMap().emplace(mHwcDisplayId, *physicalId);
                 (mIsPrimary ? flinger->mutableInternalHwcDisplayId()
                             : flinger->mutableExternalHwcDisplayId()) = mHwcDisplayId;
             }
         }
 
     private:
-        const DisplayId mDisplayId;
+        const HalDisplayId mDisplayId;
         const hal::DisplayType mHwcDisplayType;
         const bool mIsPrimary;
 
@@ -635,10 +642,10 @@
             DisplayDeviceState state;
             if (const auto type = mCreationArgs.connectionType) {
                 LOG_ALWAYS_FATAL_IF(!displayId);
+                const auto physicalId = PhysicalDisplayId::tryCast(*displayId);
+                LOG_ALWAYS_FATAL_IF(!physicalId);
                 LOG_ALWAYS_FATAL_IF(!mHwcDisplayId);
-                state.physical = {.id = static_cast<PhysicalDisplayId>(*displayId),
-                                  .type = *type,
-                                  .hwcDisplayId = *mHwcDisplayId};
+                state.physical = {.id = *physicalId, .type = *type, .hwcDisplayId = *mHwcDisplayId};
             }
 
             state.isSecure = mCreationArgs.isSecure;
@@ -672,6 +679,7 @@
     sp<SurfaceFlinger> mFlinger = new SurfaceFlinger(mFactory, SurfaceFlinger::SkipInitialization);
     TestableScheduler* mScheduler = nullptr;
     Hwc2::mock::Display mDisplay;
+    mock::DisplayIdGenerator<GpuVirtualDisplayId> mGpuVirtualDisplayIdGenerator;
 };
 
 } // namespace android
diff --git a/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockComposer.cpp b/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockComposer.cpp
index 0780af1..251ab36 100644
--- a/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockComposer.cpp
+++ b/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockComposer.cpp
@@ -20,17 +20,13 @@
 
 #include "mock/DisplayHardware/MockComposer.h"
 
-namespace android {
-namespace Hwc2 {
-namespace mock {
+namespace android::Hwc2::mock {
 
 // Explicit default instantiation is recommended.
 Composer::Composer() = default;
 Composer::~Composer() = default;
 
-} // namespace mock
-} // namespace Hwc2
-} // namespace android
+} // namespace android::Hwc2::mock
 
 // TODO(b/129481165): remove the #pragma below and fix conversion issues
 #pragma clang diagnostic pop // ignored "-Wconversion"
diff --git a/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockComposer.h b/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockComposer.h
index cd9b87a..1ba3c0f 100644
--- a/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockComposer.h
+++ b/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockComposer.h
@@ -24,8 +24,7 @@
 
 class GraphicBuffer;
 
-namespace Hwc2 {
-namespace mock {
+namespace Hwc2::mock {
 
 using android::hardware::graphics::common::V1_0::ColorTransform;
 using android::hardware::graphics::common::V1_0::Transform;
@@ -140,6 +139,5 @@
     MOCK_METHOD2(getClientTargetProperty, Error(Display, IComposerClient::ClientTargetProperty*));
 };
 
-} // namespace mock
-} // namespace Hwc2
+} // namespace Hwc2::mock
 } // namespace android
diff --git a/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockDisplay.cpp b/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockDisplay.cpp
index 2ec37c1..c9788af 100644
--- a/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockDisplay.cpp
+++ b/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockDisplay.cpp
@@ -16,14 +16,10 @@
 
 #include "mock/DisplayHardware/MockDisplay.h"
 
-namespace android {
-namespace Hwc2 {
-namespace mock {
+namespace android::Hwc2::mock {
 
 // Explicit default instantiation is recommended.
 Display::Display() = default;
 Display::~Display() = default;
 
-} // namespace mock
-} // namespace Hwc2
-} // namespace android
\ No newline at end of file
+} // namespace android::Hwc2::mock
\ No newline at end of file
diff --git a/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockDisplay.h b/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockDisplay.h
index fe99e77..a96d9db 100644
--- a/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockDisplay.h
+++ b/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockDisplay.h
@@ -22,9 +22,7 @@
 
 using android::HWC2::Layer;
 
-namespace android {
-namespace Hwc2 {
-namespace mock {
+namespace android::Hwc2::mock {
 
 namespace hal = android::hardware::graphics::composer::hal;
 
@@ -98,6 +96,4 @@
     MOCK_CONST_METHOD0(isVsyncPeriodSwitchSupported, bool());
 };
 
-} // namespace mock
-} // namespace Hwc2
-} // namespace android
+} // namespace android::Hwc2::mock
diff --git a/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockPowerAdvisor.cpp b/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockPowerAdvisor.cpp
index 8be7077..1ba38a8 100644
--- a/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockPowerAdvisor.cpp
+++ b/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockPowerAdvisor.cpp
@@ -16,14 +16,10 @@
 
 #include "MockPowerAdvisor.h"
 
-namespace android {
-namespace Hwc2 {
-namespace mock {
+namespace android::Hwc2::mock {
 
 // Explicit default instantiation is recommended.
 PowerAdvisor::PowerAdvisor() = default;
 PowerAdvisor::~PowerAdvisor() = default;
 
-} // namespace mock
-} // namespace Hwc2
-} // namespace android
+} // namespace android::Hwc2::mock
diff --git a/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockPowerAdvisor.h b/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockPowerAdvisor.h
index e22d0cf..7450b5d 100644
--- a/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockPowerAdvisor.h
+++ b/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockPowerAdvisor.h
@@ -20,9 +20,7 @@
 
 #include "DisplayHardware/PowerAdvisor.h"
 
-namespace android {
-namespace Hwc2 {
-namespace mock {
+namespace android::Hwc2::mock {
 
 class PowerAdvisor : public android::Hwc2::PowerAdvisor {
 public:
@@ -34,6 +32,4 @@
     MOCK_METHOD0(notifyDisplayUpdateImminent, void());
 };
 
-} // namespace mock
-} // namespace Hwc2
-} // namespace android
+} // namespace android::Hwc2::mock
diff --git a/services/surfaceflinger/tests/unittests/mock/MockDisplayIdGenerator.h b/services/surfaceflinger/tests/unittests/mock/MockDisplayIdGenerator.h
new file mode 100644
index 0000000..cfc37ea
--- /dev/null
+++ b/services/surfaceflinger/tests/unittests/mock/MockDisplayIdGenerator.h
@@ -0,0 +1,36 @@
+/*
+ * Copyright 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <gmock/gmock.h>
+
+#include "DisplayIdGenerator.h"
+
+namespace android::mock {
+
+template <typename T>
+class DisplayIdGenerator : public android::DisplayIdGenerator<T> {
+public:
+    // Explicit default instantiation is recommended.
+    DisplayIdGenerator() = default;
+    virtual ~DisplayIdGenerator() = default;
+
+    MOCK_METHOD0(nextId, std::optional<T>());
+    MOCK_METHOD1(markUnused, void(T));
+};
+
+} // namespace android::mock
diff --git a/services/surfaceflinger/tests/unittests/mock/MockEventThread.cpp b/services/surfaceflinger/tests/unittests/mock/MockEventThread.cpp
index 408cd35..302dc01 100644
--- a/services/surfaceflinger/tests/unittests/mock/MockEventThread.cpp
+++ b/services/surfaceflinger/tests/unittests/mock/MockEventThread.cpp
@@ -16,12 +16,10 @@
 
 #include "mock/MockEventThread.h"
 
-namespace android {
-namespace mock {
+namespace android::mock {
 
 // Explicit default instantiation is recommended.
 EventThread::EventThread() = default;
 EventThread::~EventThread() = default;
 
-} // namespace mock
-} // namespace android
+} // namespace android::mock
diff --git a/services/surfaceflinger/tests/unittests/mock/MockEventThread.h b/services/surfaceflinger/tests/unittests/mock/MockEventThread.h
index eefdec1..b4594c1 100644
--- a/services/surfaceflinger/tests/unittests/mock/MockEventThread.h
+++ b/services/surfaceflinger/tests/unittests/mock/MockEventThread.h
@@ -20,8 +20,7 @@
 
 #include "Scheduler/EventThread.h"
 
-namespace android {
-namespace mock {
+namespace android::mock {
 
 class EventThread : public android::EventThread {
 public:
@@ -47,5 +46,4 @@
     MOCK_METHOD0(getEventThreadConnectionCount, size_t());
 };
 
-} // namespace mock
-} // namespace android
+} // namespace android::mock
diff --git a/services/surfaceflinger/tests/unittests/mock/MockFrameTracer.cpp b/services/surfaceflinger/tests/unittests/mock/MockFrameTracer.cpp
index 358dfdb..417dcb0 100644
--- a/services/surfaceflinger/tests/unittests/mock/MockFrameTracer.cpp
+++ b/services/surfaceflinger/tests/unittests/mock/MockFrameTracer.cpp
@@ -16,12 +16,10 @@
 
 #include "mock/MockFrameTracer.h"
 
-namespace android {
-namespace mock {
+namespace android::mock {
 
 // Explicit default instantiation is recommended.
 FrameTracer::FrameTracer() = default;
 FrameTracer::~FrameTracer() = default;
 
-} // namespace mock
-} // namespace android
+} // namespace android::mock
diff --git a/services/surfaceflinger/tests/unittests/mock/MockFrameTracer.h b/services/surfaceflinger/tests/unittests/mock/MockFrameTracer.h
index f768b81..305cb1c 100644
--- a/services/surfaceflinger/tests/unittests/mock/MockFrameTracer.h
+++ b/services/surfaceflinger/tests/unittests/mock/MockFrameTracer.h
@@ -20,8 +20,7 @@
 
 #include "FrameTracer/FrameTracer.h"
 
-namespace android {
-namespace mock {
+namespace android::mock {
 
 class FrameTracer : public android::FrameTracer {
 public:
@@ -39,5 +38,4 @@
     MOCK_METHOD0(miniDump, std::string());
 };
 
-} // namespace mock
-} // namespace android
+} // namespace android::mock
diff --git a/services/surfaceflinger/tests/unittests/mock/MockSurfaceInterceptor.cpp b/services/surfaceflinger/tests/unittests/mock/MockSurfaceInterceptor.cpp
index 7e925b9..0a0e7b5 100644
--- a/services/surfaceflinger/tests/unittests/mock/MockSurfaceInterceptor.cpp
+++ b/services/surfaceflinger/tests/unittests/mock/MockSurfaceInterceptor.cpp
@@ -20,15 +20,13 @@
 
 #include "mock/MockSurfaceInterceptor.h"
 
-namespace android {
-namespace mock {
+namespace android::mock {
 
 // Explicit default instantiation is recommended.
 SurfaceInterceptor::SurfaceInterceptor() = default;
 SurfaceInterceptor::~SurfaceInterceptor() = default;
 
-} // namespace mock
-} // namespace android
+} // namespace android::mock
 
 // TODO(b/129481165): remove the #pragma below and fix conversion issues
 #pragma clang diagnostic pop // ignored "-Wconversion"
diff --git a/services/surfaceflinger/tests/unittests/mock/MockSurfaceInterceptor.h b/services/surfaceflinger/tests/unittests/mock/MockSurfaceInterceptor.h
index 03a04a9..b085027 100644
--- a/services/surfaceflinger/tests/unittests/mock/MockSurfaceInterceptor.h
+++ b/services/surfaceflinger/tests/unittests/mock/MockSurfaceInterceptor.h
@@ -20,8 +20,7 @@
 
 #include "SurfaceInterceptor.h"
 
-namespace android {
-namespace mock {
+namespace android::mock {
 
 class SurfaceInterceptor : public android::SurfaceInterceptor {
 public:
@@ -48,5 +47,4 @@
     MOCK_METHOD1(saveVSyncEvent, void(nsecs_t));
 };
 
-} // namespace mock
-} // namespace android
+} // namespace android::mock
diff --git a/services/surfaceflinger/tests/unittests/mock/MockTimeStats.cpp b/services/surfaceflinger/tests/unittests/mock/MockTimeStats.cpp
index d686939..f8e76b2 100644
--- a/services/surfaceflinger/tests/unittests/mock/MockTimeStats.cpp
+++ b/services/surfaceflinger/tests/unittests/mock/MockTimeStats.cpp
@@ -16,12 +16,10 @@
 
 #include "mock/MockTimeStats.h"
 
-namespace android {
-namespace mock {
+namespace android::mock {
 
 // Explicit default instantiation is recommended.
 TimeStats::TimeStats() = default;
 TimeStats::~TimeStats() = default;
 
-} // namespace mock
-} // namespace android
+} // namespace android::mock
diff --git a/services/surfaceflinger/tests/unittests/mock/MockTimeStats.h b/services/surfaceflinger/tests/unittests/mock/MockTimeStats.h
index 4186e2b..ff37ec8 100644
--- a/services/surfaceflinger/tests/unittests/mock/MockTimeStats.h
+++ b/services/surfaceflinger/tests/unittests/mock/MockTimeStats.h
@@ -20,8 +20,7 @@
 
 #include "TimeStats/TimeStats.h"
 
-namespace android {
-namespace mock {
+namespace android::mock {
 
 class TimeStats : public android::TimeStats {
 public:
@@ -59,5 +58,4 @@
     MOCK_METHOD1(setPresentFenceGlobal, void(const std::shared_ptr<FenceTime>&));
 };
 
-} // namespace mock
-} // namespace android
+} // namespace android::mock
diff --git a/services/surfaceflinger/tests/unittests/mock/MockVSyncTracker.cpp b/services/surfaceflinger/tests/unittests/mock/MockVSyncTracker.cpp
index 8a18123..bcccae5 100644
--- a/services/surfaceflinger/tests/unittests/mock/MockVSyncTracker.cpp
+++ b/services/surfaceflinger/tests/unittests/mock/MockVSyncTracker.cpp
@@ -15,15 +15,11 @@
  */
 
 #include "mock/MockVSyncTracker.h"
-#include <thread>
 
-using namespace std::chrono_literals;
-namespace android {
-namespace mock {
+namespace android::mock {
 
 // Explicit default instantiation is recommended.
 VSyncTracker::VSyncTracker() = default;
 VSyncTracker::~VSyncTracker() = default;
 
-} // namespace mock
-} // namespace android
+} // namespace android::mock
diff --git a/services/surfaceflinger/tests/unittests/mock/MockVsyncController.h b/services/surfaceflinger/tests/unittests/mock/MockVsyncController.h
index 1d87546..94d9966 100644
--- a/services/surfaceflinger/tests/unittests/mock/MockVsyncController.h
+++ b/services/surfaceflinger/tests/unittests/mock/MockVsyncController.h
@@ -20,8 +20,7 @@
 
 #include "Scheduler/VsyncController.h"
 
-namespace android {
-namespace mock {
+namespace android::mock {
 
 class VsyncController : public android::scheduler::VsyncController {
 public:
@@ -36,5 +35,4 @@
     MOCK_CONST_METHOD1(dump, void(std::string&));
 };
 
-} // namespace mock
-} // namespace android
+} // namespace android::mock