diff --git a/core/build-system.html b/core/build-system.html
index 9cd7b0b..b872909c 100644
--- a/core/build-system.html
+++ b/core/build-system.html
@@ -440,6 +440,33 @@
 LOCAL_GENERATED_SOURCES += $(GEN)
 </pre>
 
+<h3><a name="unbundled-build"/>Unbundled build</h3>
+<p>Unbundled build has several meanings by the context.
+Let me explain the meaning by the flags related to "unbundled build"</p>
+<h4>TARGET_BUILD_UNBUNDLED</h4>
+<p>The source tree might not have the full platform sources. It is always set if
+<code>TARGET_BUILD_APPS</code> or <code>TARGET_BUILD_UNBUNDLED_IMAGE</code> is set.</p>
+<h4>TARGET_BUILD_USE_PREBUILT_SDKS</h4>
+<p>It is an internal flag. If it is set, prebuilt SDKs are used, even if a module's
+<code>LOCAL_SDK_VERSION</code> is <code>current</code> (including <code>system_current</code>,
+<code>core_current</code>, and so on). If it is unset, build current SDKs,
+and use them as usual.</p>
+<h4>DISABLE_PREOPT</h4>
+<p>It is an internal flag as well. If it is set, dexpreopt is disabled.
+It is always set if <code>TARGET_BUILD_APPS</code> or <code>TARGET_BUILD_UNBUNDLED_IMAGE</code> is set,
+because dexpreopt tightly depends on the platform.</p>
+<h4>TARGET_BUILD_APPS</h4>
+<p>Build the apps that can be distributed outside the platform, so it turns on
+<code>TARGET_BUILD_UNBUNDLED</code> and <code>DISABLE_PREOPT</code>.
+Also, it turns on <code>TARGET_BUILD_USE_PREBUILT_SDKS</code>, unless
+<code>UNBUNDLED_BUILD_SDKS_FROM_SOURCE</code> is set.</p>
+<h4>TARGET_BUILD_UNBUNDLED_IMAGE</h4>
+<p>It is similar to <code>TARGET_BUILD_APPS</code>, but its target is an unbundled partition
+(such as the vendor partition). Accordingly, it sets <code>TARGET_BUILD_UNBUNDLED</code> and <code>DISABLE_PREOPT</code>.
+We can call the partition unbundled, because the partition can be distributed outside the platform.
+And also, it turns on <code>TARGET_BUILD_USE_PREBUILT_SDKS</code>, unless
+<code>UNBUNDLED_BUILD_SDKS_FROM_SOURCE</code> is set.</p>
+
 <h3><a name="platform-specific"/>Platform specific conditionals</h3>
 <p>Sometimes you need to set flags specifically for different platforms.  Here
 is a list of which values the different build-system defined variables will be
diff --git a/target/product/AndroidProducts.mk b/target/product/AndroidProducts.mk
index 3949737..8c069ba 100644
--- a/target/product/AndroidProducts.mk
+++ b/target/product/AndroidProducts.mk
@@ -55,12 +55,16 @@
     $(LOCAL_DIR)/full.mk \
     $(LOCAL_DIR)/full_x86.mk \
     $(LOCAL_DIR)/generic.mk \
+    $(LOCAL_DIR)/generic_system_arm64.mk \
+    $(LOCAL_DIR)/generic_system_x86.mk \
+    $(LOCAL_DIR)/generic_system_x86_64.mk \
+    $(LOCAL_DIR)/generic_system_x86_arm.mk \
     $(LOCAL_DIR)/generic_x86.mk \
     $(LOCAL_DIR)/gsi_arm64.mk \
     $(LOCAL_DIR)/mainline_system_arm64.mk \
     $(LOCAL_DIR)/mainline_system_x86.mk \
-    $(LOCAL_DIR)/mainline_system_x86_arm.mk \
     $(LOCAL_DIR)/mainline_system_x86_64.mk \
+    $(LOCAL_DIR)/mainline_system_x86_arm.mk \
     $(LOCAL_DIR)/sdk_arm64.mk \
     $(LOCAL_DIR)/sdk.mk \
     $(LOCAL_DIR)/sdk_phone_arm64.mk \
diff --git a/target/product/aosp_arm.mk b/target/product/aosp_arm.mk
index 0cec14b..90acc17 100644
--- a/target/product/aosp_arm.mk
+++ b/target/product/aosp_arm.mk
@@ -26,7 +26,7 @@
 #
 # All components inherited here go to system image
 #
-$(call inherit-product, $(SRC_TARGET_DIR)/product/mainline_system.mk)
+$(call inherit-product, $(SRC_TARGET_DIR)/product/generic_system.mk)
 
 # Enable mainline checking for excat this product name
 ifeq (aosp_arm,$(TARGET_PRODUCT))
diff --git a/target/product/aosp_arm64.mk b/target/product/aosp_arm64.mk
index 3254ccf..38f82a2 100644
--- a/target/product/aosp_arm64.mk
+++ b/target/product/aosp_arm64.mk
@@ -30,7 +30,7 @@
 # All components inherited here go to system image
 #
 $(call inherit-product, $(SRC_TARGET_DIR)/product/core_64_bit.mk)
-$(call inherit-product, $(SRC_TARGET_DIR)/product/mainline_system.mk)
+$(call inherit-product, $(SRC_TARGET_DIR)/product/generic_system.mk)
 
 # Enable mainline checking for excat this product name
 ifeq (aosp_arm64,$(TARGET_PRODUCT))
diff --git a/target/product/aosp_arm64_ab.mk b/target/product/aosp_arm64_ab.mk
index 0b2ae09..5510e1b 100644
--- a/target/product/aosp_arm64_ab.mk
+++ b/target/product/aosp_arm64_ab.mk
@@ -29,7 +29,7 @@
 # (The system image of Legacy GSI is not CSI)
 #
 $(call inherit-product, $(SRC_TARGET_DIR)/product/core_64_bit.mk)
-$(call inherit-product, $(SRC_TARGET_DIR)/product/mainline_system.mk)
+$(call inherit-product, $(SRC_TARGET_DIR)/product/generic_system.mk)
 
 # Enable mainline checking for excat this product name
 ifeq (aosp_arm64_ab,$(TARGET_PRODUCT))
diff --git a/target/product/aosp_arm_ab.mk b/target/product/aosp_arm_ab.mk
index ec2e5d7..7e06044 100644
--- a/target/product/aosp_arm_ab.mk
+++ b/target/product/aosp_arm_ab.mk
@@ -28,7 +28,7 @@
 # All components inherited here go to system image
 # (The system image of Legacy GSI is not CSI)
 #
-$(call inherit-product, $(SRC_TARGET_DIR)/product/mainline_system.mk)
+$(call inherit-product, $(SRC_TARGET_DIR)/product/generic_system.mk)
 
 # Enable mainline checking for excat this product name
 ifeq (aosp_arm_ab,$(TARGET_PRODUCT))
diff --git a/target/product/aosp_x86.mk b/target/product/aosp_x86.mk
index 51b5daf..7db2c0f 100644
--- a/target/product/aosp_x86.mk
+++ b/target/product/aosp_x86.mk
@@ -26,7 +26,7 @@
 #
 # All components inherited here go to system image
 #
-$(call inherit-product, $(SRC_TARGET_DIR)/product/mainline_system.mk)
+$(call inherit-product, $(SRC_TARGET_DIR)/product/generic_system.mk)
 
 # Enable mainline checking for excat this product name
 ifeq (aosp_x86,$(TARGET_PRODUCT))
diff --git a/target/product/aosp_x86_64.mk b/target/product/aosp_x86_64.mk
index 9b26716..5d78264 100644
--- a/target/product/aosp_x86_64.mk
+++ b/target/product/aosp_x86_64.mk
@@ -32,7 +32,7 @@
 # All components inherited here go to system image
 #
 $(call inherit-product, $(SRC_TARGET_DIR)/product/core_64_bit.mk)
-$(call inherit-product, $(SRC_TARGET_DIR)/product/mainline_system.mk)
+$(call inherit-product, $(SRC_TARGET_DIR)/product/generic_system.mk)
 
 # Enable mainline checking for excat this product name
 ifeq (aosp_x86_64,$(TARGET_PRODUCT))
diff --git a/target/product/aosp_x86_64_ab.mk b/target/product/aosp_x86_64_ab.mk
index 578a254..c31545d 100644
--- a/target/product/aosp_x86_64_ab.mk
+++ b/target/product/aosp_x86_64_ab.mk
@@ -29,7 +29,7 @@
 # (The system image of Legacy GSI is not CSI)
 #
 $(call inherit-product, $(SRC_TARGET_DIR)/product/core_64_bit.mk)
-$(call inherit-product, $(SRC_TARGET_DIR)/product/mainline_system.mk)
+$(call inherit-product, $(SRC_TARGET_DIR)/product/generic_system.mk)
 
 # Enable mainline checking for excat this product name
 ifeq (aosp_x86_64_ab,$(TARGET_PRODUCT))
diff --git a/target/product/aosp_x86_ab.mk b/target/product/aosp_x86_ab.mk
index 40c1d83..2f02dd1 100644
--- a/target/product/aosp_x86_ab.mk
+++ b/target/product/aosp_x86_ab.mk
@@ -29,7 +29,7 @@
 # (The system image of Legacy GSI is not CSI)
 #
 $(call inherit-product, $(SRC_TARGET_DIR)/product/core_64_bit.mk)
-$(call inherit-product, $(SRC_TARGET_DIR)/product/mainline_system.mk)
+$(call inherit-product, $(SRC_TARGET_DIR)/product/generic_system.mk)
 
 # Enable mainline checking for excat this product name
 ifeq (aosp_x86_ab,$(TARGET_PRODUCT))
diff --git a/target/product/aosp_x86_arm.mk b/target/product/aosp_x86_arm.mk
index deba3d9..f96e068 100644
--- a/target/product/aosp_x86_arm.mk
+++ b/target/product/aosp_x86_arm.mk
@@ -19,7 +19,7 @@
 #
 # All components inherited here go to system image
 #
-$(call inherit-product, $(SRC_TARGET_DIR)/product/mainline_system.mk)
+$(call inherit-product, $(SRC_TARGET_DIR)/product/generic_system.mk)
 
 # Enable mainline checking
 ifeq (aosp_x86_arm,$(TARGET_PRODUCT))
diff --git a/target/product/mainline_system.mk b/target/product/generic_system.mk
similarity index 98%
rename from target/product/mainline_system.mk
rename to target/product/generic_system.mk
index e3b3e7d..e59e93e 100644
--- a/target/product/mainline_system.mk
+++ b/target/product/generic_system.mk
@@ -128,11 +128,11 @@
 # TODO(b/150820813) Settings depends on static overlay, remove this after eliminating the dependency.
 PRODUCT_ENFORCE_RRO_EXEMPTED_TARGETS := Settings
 
-PRODUCT_NAME := mainline_system
+PRODUCT_NAME := generic_system
 PRODUCT_BRAND := generic
 
 # Define /system partition-specific product properties to identify that /system
-# partition is mainline_system.
+# partition is generic_system.
 PRODUCT_SYSTEM_NAME := mainline
 PRODUCT_SYSTEM_BRAND := Android
 PRODUCT_SYSTEM_MANUFACTURER := Android
diff --git a/target/product/generic_system_arm64.mk b/target/product/generic_system_arm64.mk
new file mode 100644
index 0000000..b8b12c3
--- /dev/null
+++ b/target/product/generic_system_arm64.mk
@@ -0,0 +1,46 @@
+#
+# Copyright (C) 2018 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.
+#
+
+#
+# All components inherited here go to system image
+#
+$(call inherit-product, $(SRC_TARGET_DIR)/product/core_64_bit.mk)
+$(call inherit-product, $(SRC_TARGET_DIR)/product/generic_system.mk)
+$(call enforce-product-packages-exist,)
+
+# Enable mainline checking
+PRODUCT_ENFORCE_ARTIFACT_PATH_REQUIREMENTS := true
+
+PRODUCT_BUILD_CACHE_IMAGE := false
+PRODUCT_BUILD_ODM_IMAGE := false
+PRODUCT_BUILD_VENDOR_DLKM_IMAGE := false
+PRODUCT_BUILD_ODM_DLKM_IMAGE := false
+PRODUCT_BUILD_PRODUCT_IMAGE  := false
+PRODUCT_BUILD_RAMDISK_IMAGE := false
+PRODUCT_BUILD_SYSTEM_IMAGE := true
+PRODUCT_BUILD_SYSTEM_EXT_IMAGE := false
+PRODUCT_BUILD_SYSTEM_OTHER_IMAGE := false
+PRODUCT_BUILD_USERDATA_IMAGE := false
+PRODUCT_BUILD_VENDOR_IMAGE := false
+
+PRODUCT_SHIPPING_API_LEVEL := 29
+
+# TODO(b/137033385): change this back to "all"
+PRODUCT_RESTRICT_VENDOR_FILES := owner
+
+PRODUCT_NAME := generic_system_arm64
+PRODUCT_DEVICE := mainline_arm64
+PRODUCT_BRAND := generic
diff --git a/target/product/generic_system_x86.mk b/target/product/generic_system_x86.mk
new file mode 100644
index 0000000..dddcb7e
--- /dev/null
+++ b/target/product/generic_system_x86.mk
@@ -0,0 +1,45 @@
+#
+# Copyright (C) 2019 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.
+#
+
+#
+# All components inherited here go to system image
+#
+$(call inherit-product, $(SRC_TARGET_DIR)/product/generic_system.mk)
+$(call enforce-product-packages-exist,)
+
+# Enable mainline checking
+PRODUCT_ENFORCE_ARTIFACT_PATH_REQUIREMENTS := true
+
+PRODUCT_BUILD_CACHE_IMAGE := false
+PRODUCT_BUILD_ODM_IMAGE := false
+PRODUCT_BUILD_VENDOR_DLKM_IMAGE := false
+PRODUCT_BUILD_ODM_DLKM_IMAGE := false
+PRODUCT_BUILD_PRODUCT_IMAGE  := false
+PRODUCT_BUILD_RAMDISK_IMAGE := false
+PRODUCT_BUILD_SYSTEM_IMAGE := true
+PRODUCT_BUILD_SYSTEM_EXT_IMAGE := false
+PRODUCT_BUILD_SYSTEM_OTHER_IMAGE := false
+PRODUCT_BUILD_USERDATA_IMAGE := false
+PRODUCT_BUILD_VENDOR_IMAGE := false
+
+PRODUCT_SHIPPING_API_LEVEL := 29
+
+# TODO(b/137033385): change this back to "all"
+PRODUCT_RESTRICT_VENDOR_FILES := owner
+
+PRODUCT_NAME := generic_system_x86
+PRODUCT_DEVICE := mainline_x86
+PRODUCT_BRAND := generic
diff --git a/target/product/generic_system_x86_64.mk b/target/product/generic_system_x86_64.mk
new file mode 100644
index 0000000..1ca9678
--- /dev/null
+++ b/target/product/generic_system_x86_64.mk
@@ -0,0 +1,45 @@
+#
+# Copyright (C) 2019 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.
+#
+
+#
+# All components inherited here go to system image
+#
+$(call inherit-product, $(SRC_TARGET_DIR)/product/core_64_bit.mk)
+$(call inherit-product, $(SRC_TARGET_DIR)/product/generic_system.mk)
+$(call enforce-product-packages-exist,)
+
+# Enable mainline checking
+PRODUCT_ENFORCE_ARTIFACT_PATH_REQUIREMENTS := true
+
+PRODUCT_BUILD_CACHE_IMAGE := false
+PRODUCT_BUILD_ODM_IMAGE := false
+PRODUCT_BUILD_VENDOR_DLKM_IMAGE := false
+PRODUCT_BUILD_ODM_DLKM_IMAGE := false
+PRODUCT_BUILD_PRODUCT_IMAGE  := false
+PRODUCT_BUILD_RAMDISK_IMAGE := false
+PRODUCT_BUILD_SYSTEM_IMAGE := true
+PRODUCT_BUILD_SYSTEM_EXT_IMAGE := false
+PRODUCT_BUILD_SYSTEM_OTHER_IMAGE := false
+PRODUCT_BUILD_USERDATA_IMAGE := false
+PRODUCT_BUILD_VENDOR_IMAGE := false
+
+PRODUCT_SHIPPING_API_LEVEL := 29
+
+PRODUCT_RESTRICT_VENDOR_FILES := all
+
+PRODUCT_NAME := generic_system_x86_64
+PRODUCT_DEVICE := mainline_x86_64
+PRODUCT_BRAND := generic
diff --git a/target/product/generic_system_x86_arm.mk b/target/product/generic_system_x86_arm.mk
new file mode 100644
index 0000000..a62fb9b
--- /dev/null
+++ b/target/product/generic_system_x86_arm.mk
@@ -0,0 +1,45 @@
+#
+# Copyright (C) 2019 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.
+#
+
+#
+# All components inherited here go to system image
+#
+$(call inherit-product, $(SRC_TARGET_DIR)/product/generic_system.mk)
+$(call enforce-product-packages-exist,)
+
+# Enable mainline checking
+PRODUCT_ENFORCE_ARTIFACT_PATH_REQUIREMENTS := true
+
+PRODUCT_BUILD_CACHE_IMAGE := false
+PRODUCT_BUILD_ODM_IMAGE := false
+PRODUCT_BUILD_VENDOR_DLKM_IMAGE := false
+PRODUCT_BUILD_ODM_DLKM_IMAGE := false
+PRODUCT_BUILD_PRODUCT_IMAGE  := false
+PRODUCT_BUILD_RAMDISK_IMAGE := false
+PRODUCT_BUILD_SYSTEM_IMAGE := true
+PRODUCT_BUILD_SYSTEM_EXT_IMAGE := false
+PRODUCT_BUILD_SYSTEM_OTHER_IMAGE := false
+PRODUCT_BUILD_USERDATA_IMAGE := false
+PRODUCT_BUILD_VENDOR_IMAGE := false
+
+PRODUCT_SHIPPING_API_LEVEL := 29
+
+# TODO(b/137033385): change this back to "all"
+PRODUCT_RESTRICT_VENDOR_FILES := owner
+
+PRODUCT_NAME := generic_system_x86_arm
+PRODUCT_DEVICE := mainline_x86_arm
+PRODUCT_BRAND := generic
diff --git a/target/product/gsi_arm64.mk b/target/product/gsi_arm64.mk
index adf7ca5..1043a85 100644
--- a/target/product/gsi_arm64.mk
+++ b/target/product/gsi_arm64.mk
@@ -18,7 +18,7 @@
 # All components inherited here go to system image
 #
 $(call inherit-product, $(SRC_TARGET_DIR)/product/core_64_bit.mk)
-$(call inherit-product, $(SRC_TARGET_DIR)/product/mainline_system.mk)
+$(call inherit-product, $(SRC_TARGET_DIR)/product/generic_system.mk)
 
 # Enable mainline checking
 PRODUCT_ENFORCE_ARTIFACT_PATH_REQUIREMENTS := relaxed
diff --git a/target/product/mainline_system.mk b/target/product/mainline_system.mk
new file mode 120000
index 0000000..0b6eaf0
--- /dev/null
+++ b/target/product/mainline_system.mk
@@ -0,0 +1 @@
+generic_system.mk
\ No newline at end of file
diff --git a/target/product/mainline_system_arm64.mk b/target/product/mainline_system_arm64.mk
index a0c3e6d..5fa13ce 100644
--- a/target/product/mainline_system_arm64.mk
+++ b/target/product/mainline_system_arm64.mk
@@ -14,33 +14,10 @@
 # limitations under the License.
 #
 
-#
-# All components inherited here go to system image
-#
-$(call inherit-product, $(SRC_TARGET_DIR)/product/core_64_bit.mk)
-$(call inherit-product, $(SRC_TARGET_DIR)/product/mainline_system.mk)
-$(call enforce-product-packages-exist,)
+# Do not modify this file. It's just alias of generic_system_arm64.mk
+# Will be removed when renaming from mainline_system to generic_system
+# complete
 
-# Enable mainline checking
-PRODUCT_ENFORCE_ARTIFACT_PATH_REQUIREMENTS := true
-
-PRODUCT_BUILD_CACHE_IMAGE := false
-PRODUCT_BUILD_ODM_IMAGE := false
-PRODUCT_BUILD_VENDOR_DLKM_IMAGE := false
-PRODUCT_BUILD_ODM_DLKM_IMAGE := false
-PRODUCT_BUILD_PRODUCT_IMAGE  := false
-PRODUCT_BUILD_RAMDISK_IMAGE := false
-PRODUCT_BUILD_SYSTEM_IMAGE := true
-PRODUCT_BUILD_SYSTEM_EXT_IMAGE := false
-PRODUCT_BUILD_SYSTEM_OTHER_IMAGE := false
-PRODUCT_BUILD_USERDATA_IMAGE := false
-PRODUCT_BUILD_VENDOR_IMAGE := false
-
-PRODUCT_SHIPPING_API_LEVEL := 29
-
-# TODO(b/137033385): change this back to "all"
-PRODUCT_RESTRICT_VENDOR_FILES := owner
+$(call inherit-product, $(SRC_TARGET_DIR)/product/generic_system_arm64.mk)
 
 PRODUCT_NAME := mainline_system_arm64
-PRODUCT_DEVICE := mainline_arm64
-PRODUCT_BRAND := generic
diff --git a/target/product/mainline_system_x86.mk b/target/product/mainline_system_x86.mk
index 3c4a867..3fb1963 100644
--- a/target/product/mainline_system_x86.mk
+++ b/target/product/mainline_system_x86.mk
@@ -14,32 +14,10 @@
 # limitations under the License.
 #
 
-#
-# All components inherited here go to system image
-#
-$(call inherit-product, $(SRC_TARGET_DIR)/product/mainline_system.mk)
-$(call enforce-product-packages-exist,)
+# Do not modify this file. It's just alias of generic_system_x86.mk
+# Will be removed when renaming from mainline_system to generic_system
+# complete
 
-# Enable mainline checking
-PRODUCT_ENFORCE_ARTIFACT_PATH_REQUIREMENTS := true
-
-PRODUCT_BUILD_CACHE_IMAGE := false
-PRODUCT_BUILD_ODM_IMAGE := false
-PRODUCT_BUILD_VENDOR_DLKM_IMAGE := false
-PRODUCT_BUILD_ODM_DLKM_IMAGE := false
-PRODUCT_BUILD_PRODUCT_IMAGE  := false
-PRODUCT_BUILD_RAMDISK_IMAGE := false
-PRODUCT_BUILD_SYSTEM_IMAGE := true
-PRODUCT_BUILD_SYSTEM_EXT_IMAGE := false
-PRODUCT_BUILD_SYSTEM_OTHER_IMAGE := false
-PRODUCT_BUILD_USERDATA_IMAGE := false
-PRODUCT_BUILD_VENDOR_IMAGE := false
-
-PRODUCT_SHIPPING_API_LEVEL := 29
-
-# TODO(b/137033385): change this back to "all"
-PRODUCT_RESTRICT_VENDOR_FILES := owner
+$(call inherit-product, $(SRC_TARGET_DIR)/product/generic_system_x86.mk)
 
 PRODUCT_NAME := mainline_system_x86
-PRODUCT_DEVICE := mainline_x86
-PRODUCT_BRAND := generic
diff --git a/target/product/mainline_system_x86_64.mk b/target/product/mainline_system_x86_64.mk
index 410c998..eab99c5 100644
--- a/target/product/mainline_system_x86_64.mk
+++ b/target/product/mainline_system_x86_64.mk
@@ -14,32 +14,10 @@
 # limitations under the License.
 #
 
-#
-# All components inherited here go to system image
-#
-$(call inherit-product, $(SRC_TARGET_DIR)/product/core_64_bit.mk)
-$(call inherit-product, $(SRC_TARGET_DIR)/product/mainline_system.mk)
-$(call enforce-product-packages-exist,)
+# Do not modify this file. It's just alias of generic_system_x86_64.mk
+# Will be removed when renaming from mainline_system to generic_system
+# complete
 
-# Enable mainline checking
-PRODUCT_ENFORCE_ARTIFACT_PATH_REQUIREMENTS := true
-
-PRODUCT_BUILD_CACHE_IMAGE := false
-PRODUCT_BUILD_ODM_IMAGE := false
-PRODUCT_BUILD_VENDOR_DLKM_IMAGE := false
-PRODUCT_BUILD_ODM_DLKM_IMAGE := false
-PRODUCT_BUILD_PRODUCT_IMAGE  := false
-PRODUCT_BUILD_RAMDISK_IMAGE := false
-PRODUCT_BUILD_SYSTEM_IMAGE := true
-PRODUCT_BUILD_SYSTEM_EXT_IMAGE := false
-PRODUCT_BUILD_SYSTEM_OTHER_IMAGE := false
-PRODUCT_BUILD_USERDATA_IMAGE := false
-PRODUCT_BUILD_VENDOR_IMAGE := false
-
-PRODUCT_SHIPPING_API_LEVEL := 29
-
-PRODUCT_RESTRICT_VENDOR_FILES := all
+$(call inherit-product, $(SRC_TARGET_DIR)/product/generic_system_x86_64.mk)
 
 PRODUCT_NAME := mainline_system_x86_64
-PRODUCT_DEVICE := mainline_x86_64
-PRODUCT_BRAND := generic
diff --git a/target/product/mainline_system_x86_arm.mk b/target/product/mainline_system_x86_arm.mk
index 8c6611e..483fb58 100644
--- a/target/product/mainline_system_x86_arm.mk
+++ b/target/product/mainline_system_x86_arm.mk
@@ -14,32 +14,10 @@
 # limitations under the License.
 #
 
-#
-# All components inherited here go to system image
-#
-$(call inherit-product, $(SRC_TARGET_DIR)/product/mainline_system.mk)
-$(call enforce-product-packages-exist,)
+# Do not modify this file. It's just alias of generic_system_x86_arm.mk
+# Will be removed when renaming from mainline_system to generic_system
+# complete
 
-# Enable mainline checking
-PRODUCT_ENFORCE_ARTIFACT_PATH_REQUIREMENTS := true
-
-PRODUCT_BUILD_CACHE_IMAGE := false
-PRODUCT_BUILD_ODM_IMAGE := false
-PRODUCT_BUILD_VENDOR_DLKM_IMAGE := false
-PRODUCT_BUILD_ODM_DLKM_IMAGE := false
-PRODUCT_BUILD_PRODUCT_IMAGE  := false
-PRODUCT_BUILD_RAMDISK_IMAGE := false
-PRODUCT_BUILD_SYSTEM_IMAGE := true
-PRODUCT_BUILD_SYSTEM_EXT_IMAGE := false
-PRODUCT_BUILD_SYSTEM_OTHER_IMAGE := false
-PRODUCT_BUILD_USERDATA_IMAGE := false
-PRODUCT_BUILD_VENDOR_IMAGE := false
-
-PRODUCT_SHIPPING_API_LEVEL := 29
-
-# TODO(b/137033385): change this back to "all"
-PRODUCT_RESTRICT_VENDOR_FILES := owner
+$(call inherit-product, $(SRC_TARGET_DIR)/product/generic_system_x86_arm.mk)
 
 PRODUCT_NAME := mainline_system_x86_arm
-PRODUCT_DEVICE := mainline_x86_arm
-PRODUCT_BRAND := generic
diff --git a/target/product/sdk_phone_arm64.mk b/target/product/sdk_phone_arm64.mk
index cefa288..761de05 100644
--- a/target/product/sdk_phone_arm64.mk
+++ b/target/product/sdk_phone_arm64.mk
@@ -30,7 +30,7 @@
 # All components inherited here go to system image
 #
 $(call inherit-product, $(SRC_TARGET_DIR)/product/core_64_bit.mk)
-$(call inherit-product, $(SRC_TARGET_DIR)/product/mainline_system.mk)
+$(call inherit-product, $(SRC_TARGET_DIR)/product/generic_system.mk)
 
 #
 # All components inherited here go to system_ext image
diff --git a/target/product/sdk_phone_armv7.mk b/target/product/sdk_phone_armv7.mk
index c4c5a38..5081a87 100644
--- a/target/product/sdk_phone_armv7.mk
+++ b/target/product/sdk_phone_armv7.mk
@@ -29,7 +29,7 @@
 #
 # All components inherited here go to system image
 #
-$(call inherit-product, $(SRC_TARGET_DIR)/product/mainline_system.mk)
+$(call inherit-product, $(SRC_TARGET_DIR)/product/generic_system.mk)
 
 #
 # All components inherited here go to system_ext image
diff --git a/target/product/sdk_phone_x86.mk b/target/product/sdk_phone_x86.mk
index bcee066..63671dc 100644
--- a/target/product/sdk_phone_x86.mk
+++ b/target/product/sdk_phone_x86.mk
@@ -24,7 +24,7 @@
 #
 # All components inherited here go to system image
 #
-$(call inherit-product, $(SRC_TARGET_DIR)/product/mainline_system.mk)
+$(call inherit-product, $(SRC_TARGET_DIR)/product/generic_system.mk)
 
 # Enable mainline checking for exact this product name
 ifeq (sdk_phone_x86,$(TARGET_PRODUCT))
diff --git a/target/product/sdk_phone_x86_64.mk b/target/product/sdk_phone_x86_64.mk
index 82bbee5..c5a6245 100644
--- a/target/product/sdk_phone_x86_64.mk
+++ b/target/product/sdk_phone_x86_64.mk
@@ -25,7 +25,7 @@
 # All components inherited here go to system image
 #
 $(call inherit-product, $(SRC_TARGET_DIR)/product/core_64_bit.mk)
-$(call inherit-product, $(SRC_TARGET_DIR)/product/mainline_system.mk)
+$(call inherit-product, $(SRC_TARGET_DIR)/product/generic_system.mk)
 
 # Enable mainline checking for exact this product name
 ifeq (sdk_phone_x86_64,$(TARGET_PRODUCT))