diff --git a/android/TerminalApp/java/com/android/virtualization/terminal/ImageArchive.java b/android/TerminalApp/java/com/android/virtualization/terminal/ImageArchive.java
index b2a2085..7f14179 100644
--- a/android/TerminalApp/java/com/android/virtualization/terminal/ImageArchive.java
+++ b/android/TerminalApp/java/com/android/virtualization/terminal/ImageArchive.java
@@ -16,8 +16,11 @@
 
 package com.android.virtualization.terminal;
 
+import static com.android.virtualization.terminal.MainActivity.TAG;
+
 import android.os.Build;
 import android.os.Environment;
+import android.util.Log;
 
 import org.apache.commons.compress.archivers.ArchiveEntry;
 import org.apache.commons.compress.archivers.tar.TarArchiveInputStream;
@@ -43,7 +46,8 @@
 class ImageArchive {
     private static final String DIR_IN_SDCARD = "linux";
     private static final String ARCHIVE_NAME = "images.tar.gz";
-    private static final String HOST_URL = "https://dl.google.com/android/ferrochrome/latest";
+    private static final String BUILD_TAG = "latest"; // TODO: use actual tag name
+    private static final String HOST_URL = "https://dl.google.com/android/ferrochrome/" + BUILD_TAG;
 
     // Only one can be non-null
     private final URL mUrl;
@@ -138,6 +142,8 @@
      * an additional input stream which will be used during the installation.
      */
     public void installTo(Path dir, Function<InputStream, InputStream> filter) throws IOException {
+        String source = mPath != null ? mPath.toString() : mUrl.toString();
+        Log.d(TAG, "Installing. source: " + source + ", destination: " + dir.toString());
         try (InputStream stream = getInputStream(filter);
                 GzipCompressorInputStream gzStream = new GzipCompressorInputStream(stream);
                 TarArchiveInputStream tarStream = new TarArchiveInputStream(gzStream)) {
@@ -148,9 +154,9 @@
                 Path to = dir.resolve(entry.getName());
                 if (Files.isDirectory(to)) {
                     Files.createDirectories(to);
-                } else {
-                    Files.copy(tarStream, to, StandardCopyOption.REPLACE_EXISTING);
+                    continue;
                 }
+                Files.copy(tarStream, to, StandardCopyOption.REPLACE_EXISTING);
             }
         }
         commitInstallationAt(dir);
diff --git a/android/TerminalApp/java/com/android/virtualization/terminal/InstalledImage.java b/android/TerminalApp/java/com/android/virtualization/terminal/InstalledImage.java
index f318358..318f49a 100644
--- a/android/TerminalApp/java/com/android/virtualization/terminal/InstalledImage.java
+++ b/android/TerminalApp/java/com/android/virtualization/terminal/InstalledImage.java
@@ -23,7 +23,9 @@
 import android.system.Os;
 import android.util.Log;
 
+import java.io.BufferedReader;
 import java.io.FileDescriptor;
+import java.io.FileReader;
 import java.io.IOException;
 import java.io.RandomAccessFile;
 import java.nio.file.Files;
@@ -36,6 +38,7 @@
     private static final String ROOTFS_FILENAME = "root_part";
     private static final String BACKUP_FILENAME = "root_part_backup";
     private static final String CONFIG_FILENAME = "vm_config.json";
+    private static final String BUILD_ID_FILENAME = "build_id";
     static final String MARKER_FILENAME = "completed";
 
     public static final long RESIZE_STEP_BYTES = 4 << 20; // 4 MiB
@@ -45,6 +48,7 @@
     private final Path mBackup;
     private final Path mConfig;
     private final Path mMarker;
+    private String mBuildId;
 
     /** Returns InstalledImage for a given app context */
     public static InstalledImage getDefault(Context context) {
@@ -79,6 +83,26 @@
         return mConfig;
     }
 
+    /** Returns the build ID of the installed image */
+    public String getBuildId() {
+        if (mBuildId == null) {
+            mBuildId = readBuildId();
+        }
+        return mBuildId;
+    }
+
+    private String readBuildId() {
+        Path file = mDir.resolve(BUILD_ID_FILENAME);
+        if (!Files.exists(file)) {
+            return "<no build id>";
+        }
+        try (BufferedReader r = new BufferedReader(new FileReader(file.toFile()))) {
+            return r.readLine();
+        } catch (IOException e) {
+            throw new RuntimeException("Failed to read build ID", e);
+        }
+    }
+
     public Path uninstallAndBackup() throws IOException {
         Files.delete(mMarker);
         Files.move(mRootPartition, mBackup, StandardCopyOption.REPLACE_EXISTING);
diff --git a/android/TerminalApp/java/com/android/virtualization/terminal/InstallerService.java b/android/TerminalApp/java/com/android/virtualization/terminal/InstallerService.java
index c2b3fd4..ac05d78 100644
--- a/android/TerminalApp/java/com/android/virtualization/terminal/InstallerService.java
+++ b/android/TerminalApp/java/com/android/virtualization/terminal/InstallerService.java
@@ -48,11 +48,6 @@
 public class InstallerService extends Service {
     private static final int NOTIFICATION_ID = 1313; // any unique number among notifications
 
-    private static final String IMAGE_URL =
-            Arrays.asList(Build.SUPPORTED_ABIS).contains("x86_64")
-                    ? "https://dl.google.com/android/ferrochrome/latest/x86_64/images.tar.gz"
-                    : "https://dl.google.com/android/ferrochrome/latest/aarch64/images.tar.gz";
-
     private final Object mLock = new Object();
 
     private Notification mNotification;
@@ -191,8 +186,6 @@
 
     // TODO(b/374015561): Support pause/resume download
     private boolean downloadFromUrl(boolean isWifiOnly) {
-        Log.i(TAG, "trying to download from " + IMAGE_URL);
-
         if (!checkForWifiOnly(isWifiOnly)) {
             Log.e(TAG, "Install isn't started because Wifi isn't available");
             notifyError(getString(R.string.installer_error_no_wifi));
diff --git a/android/compos_verify/verify.rs b/android/compos_verify/verify.rs
index a3f18d5..b94ebbc 100644
--- a/android/compos_verify/verify.rs
+++ b/android/compos_verify/verify.rs
@@ -124,6 +124,7 @@
         &idsig_manifest_ext_apk,
         &VmParameters {
             name: String::from("ComposVerify"),
+            os: String::from("microdroid"),
             cpu_topology: VmCpuTopology::OneCpu, // This VM runs very little work at boot
             debug_mode: args.debug,
             ..Default::default()
diff --git a/android/composd/aidl/android/system/composd/IIsolatedCompilationService.aidl b/android/composd/aidl/android/system/composd/IIsolatedCompilationService.aidl
index dde75e1..3748899 100644
--- a/android/composd/aidl/android/system/composd/IIsolatedCompilationService.aidl
+++ b/android/composd/aidl/android/system/composd/IIsolatedCompilationService.aidl
@@ -48,5 +48,6 @@
      * callback, unless the returned ICompilationTask is cancelled. The caller should maintain
      * a reference to the ICompilationTask until compilation completes or is cancelled.
      */
-    ICompilationTask startTestCompile(ApexSource apexSource, ICompilationTaskCallback callback);
+    ICompilationTask startTestCompile(
+            ApexSource apexSource, ICompilationTaskCallback callback, String os);
 }
diff --git a/android/composd/src/instance_manager.rs b/android/composd/src/instance_manager.rs
index 9e94035..d1b0b99 100644
--- a/android/composd/src/instance_manager.rs
+++ b/android/composd/src/instance_manager.rs
@@ -46,11 +46,12 @@
         self.start_instance(CURRENT_INSTANCE_DIR, vm_parameters)
     }
 
-    pub fn start_test_instance(&self, prefer_staged: bool) -> Result<CompOsInstance> {
+    pub fn start_test_instance(&self, prefer_staged: bool, os: &str) -> Result<CompOsInstance> {
         let mut vm_parameters = new_vm_parameters()?;
         vm_parameters.name = String::from("ComposdTest");
         vm_parameters.debug_mode = true;
         vm_parameters.prefer_staged = prefer_staged;
+        vm_parameters.os = os.to_owned();
         self.start_instance(TEST_INSTANCE_DIR, vm_parameters)
     }
 
@@ -83,7 +84,8 @@
     // number of dex2oat threads.
     let cpu_topology = VmCpuTopology::MatchHost;
     let memory_mib = Some(compos_memory_mib()?);
-    Ok(VmParameters { cpu_topology, memory_mib, ..Default::default() })
+    let os = "microdroid".to_owned();
+    Ok(VmParameters { cpu_topology, memory_mib, os, ..Default::default() })
 }
 
 fn compos_memory_mib() -> Result<i32> {
diff --git a/android/composd/src/service.rs b/android/composd/src/service.rs
index 49cfd3a..3cc40af 100644
--- a/android/composd/src/service.rs
+++ b/android/composd/src/service.rs
@@ -60,6 +60,7 @@
         &self,
         apex_source: ApexSource,
         callback: &Strong<dyn ICompilationTaskCallback>,
+        os: &str,
     ) -> binder::Result<Strong<dyn ICompilationTask>> {
         check_permissions()?;
         let prefer_staged = match apex_source {
@@ -67,7 +68,7 @@
             ApexSource::PreferStaged => true,
             _ => unreachable!("Invalid ApexSource {:?}", apex_source),
         };
-        to_binder_result(self.do_start_test_compile(prefer_staged, callback))
+        to_binder_result(self.do_start_test_compile(prefer_staged, callback, os))
     }
 }
 
@@ -93,9 +94,12 @@
         &self,
         prefer_staged: bool,
         callback: &Strong<dyn ICompilationTaskCallback>,
+        os: &str,
     ) -> Result<Strong<dyn ICompilationTask>> {
-        let comp_os =
-            self.instance_manager.start_test_instance(prefer_staged).context("Starting CompOS")?;
+        let comp_os = self
+            .instance_manager
+            .start_test_instance(prefer_staged, os)
+            .context("Starting CompOS")?;
 
         let target_dir_name = TEST_ARTIFACTS_SUBDIR.to_owned();
         let task = OdrefreshTask::start(
diff --git a/android/composd_cmd/composd_cmd.rs b/android/composd_cmd/composd_cmd.rs
index 6d096a1..6281bd0 100644
--- a/android/composd_cmd/composd_cmd.rs
+++ b/android/composd_cmd/composd_cmd.rs
@@ -46,6 +46,10 @@
         /// If any APEX is staged, prefer the staged version.
         #[clap(long)]
         prefer_staged: bool,
+
+        /// OS for the VM.
+        #[clap(long, default_value = "microdroid")]
+        os: String,
     },
 }
 
@@ -56,7 +60,7 @@
 
     match action {
         Actions::StagedApexCompile {} => run_staged_apex_compile()?,
-        Actions::TestCompile { prefer_staged } => run_test_compile(prefer_staged)?,
+        Actions::TestCompile { prefer_staged, os } => run_test_compile(prefer_staged, &os)?,
     }
 
     println!("All Ok!");
@@ -116,9 +120,9 @@
     run_async_compilation(|service, callback| service.startStagedApexCompile(callback))
 }
 
-fn run_test_compile(prefer_staged: bool) -> Result<()> {
+fn run_test_compile(prefer_staged: bool, os: &str) -> Result<()> {
     let apex_source = if prefer_staged { ApexSource::PreferStaged } else { ApexSource::NoStaged };
-    run_async_compilation(|service, callback| service.startTestCompile(apex_source, callback))
+    run_async_compilation(|service, callback| service.startTestCompile(apex_source, callback, os))
 }
 
 fn run_async_compilation<F>(start_compile_fn: F) -> Result<()>
diff --git a/guest/pvmfw/src/entry.rs b/guest/pvmfw/src/entry.rs
index ce911b8..48585f3 100644
--- a/guest/pvmfw/src/entry.rs
+++ b/guest/pvmfw/src/entry.rs
@@ -129,7 +129,7 @@
         page_table,
         crosvm::MEM_START..layout::MAX_VIRT_ADDR,
         crosvm::MMIO_RANGE,
-        Some(memory::appended_payload_range()),
+        Some(layout::image_footer_range()),
     ));
 
     let slices = memory::MemorySlices::new(
@@ -189,7 +189,7 @@
 
     const SCTLR_EL1_VAL: u64 = SCTLR_EL1_RES1 | SCTLR_EL1_ITD | SCTLR_EL1_SED | SCTLR_EL1_I;
 
-    let scratch = layout::scratch_range();
+    let scratch = layout::data_bss_range();
 
     assert_ne!(scratch.end - scratch.start, 0, "scratch memory is empty.");
     assert_eq!(scratch.start.0 % ASM_STP_ALIGN, 0, "scratch memory is misaligned.");
@@ -205,6 +205,12 @@
     assert_eq!(stack.start.0 % ASM_STP_ALIGN, 0, "Misaligned stack region.");
     assert_eq!(stack.end.0 % ASM_STP_ALIGN, 0, "Misaligned stack region.");
 
+    let eh_stack = layout::eh_stack_range();
+
+    assert_ne!(eh_stack.end - eh_stack.start, 0, "EH stack region is empty.");
+    assert_eq!(eh_stack.start.0 % ASM_STP_ALIGN, 0, "Misaligned EH stack region.");
+    assert_eq!(eh_stack.end.0 % ASM_STP_ALIGN, 0, "Misaligned EH stack region.");
+
     // Zero all memory that could hold secrets and that can't be safely written to from Rust.
     // Disable the exception vector, caches and page table and then jump to the payload at the
     // given address, passing it the given FDT pointer.
@@ -250,6 +256,18 @@
             "cmp {cache_line}, {stack_end}",
             "b.lo 0b",
 
+            "mov {cache_line}, {eh_stack}",
+            // Zero EH stack region.
+            "0: stp xzr, xzr, [{eh_stack}], 16",
+            "cmp {eh_stack}, {eh_stack_end}",
+            "b.lo 0b",
+
+            // Flush d-cache over EH stack region.
+            "0: dc cvau, {cache_line}",
+            "add {cache_line}, {cache_line}, {dcache_line_size}",
+            "cmp {cache_line}, {eh_stack_end}",
+            "b.lo 0b",
+
             "msr sctlr_el1, {sctlr_el1_val}",
             "isb",
             "mov x1, xzr",
@@ -293,6 +311,8 @@
             scratch_end = in(reg) u64::try_from(scratch.end.0).unwrap(),
             stack = in(reg) u64::try_from(stack.start.0).unwrap(),
             stack_end = in(reg) u64::try_from(stack.end.0).unwrap(),
+            eh_stack = in(reg) u64::try_from(eh_stack.start.0).unwrap(),
+            eh_stack_end = in(reg) u64::try_from(eh_stack.end.0).unwrap(),
             dcache_line_size = in(reg) u64::try_from(min_dcache_line_size()).unwrap(),
             in("x0") fdt_address,
             in("x30") payload_start,
@@ -306,7 +326,7 @@
 /// This must only be called once, since we are returning a mutable reference.
 /// The appended data region must be mapped.
 unsafe fn get_appended_data_slice() -> &'static mut [u8] {
-    let range = memory::appended_payload_range();
+    let range = layout::image_footer_range();
     // SAFETY: This region is mapped and the linker script prevents it from overlapping with other
     // objects.
     unsafe { slice::from_raw_parts_mut(range.start.0 as *mut u8, range.end - range.start) }
diff --git a/guest/pvmfw/src/memory.rs b/guest/pvmfw/src/memory.rs
index 8e8b338..7d49bca 100644
--- a/guest/pvmfw/src/memory.rs
+++ b/guest/pvmfw/src/memory.rs
@@ -30,18 +30,9 @@
 use log::warn;
 use vmbase::{
     layout::{self, crosvm},
-    memory::{PageTable, MEMORY, SIZE_2MB, SIZE_4KB},
-    util::align_up,
+    memory::{PageTable, MEMORY},
 };
 
-/// Returns memory range reserved for the appended payload.
-pub fn appended_payload_range() -> Range<VirtualAddress> {
-    let start = align_up(layout::binary_end().0, SIZE_4KB).unwrap();
-    // pvmfw is contained in a 2MiB region so the payload can't be larger than the 2MiB alignment.
-    let end = align_up(start, SIZE_2MB).unwrap();
-    VirtualAddress(start)..VirtualAddress(end)
-}
-
 /// Region allocated for the stack.
 pub fn stack_range() -> Range<VirtualAddress> {
     const STACK_PAGES: usize = 12;
@@ -54,11 +45,12 @@
 
     // Stack and scratch ranges are explicitly zeroed and flushed before jumping to payload,
     // so dirty state management can be omitted.
-    page_table.map_data(&layout::scratch_range().into())?;
+    page_table.map_data(&layout::data_bss_range().into())?;
+    page_table.map_data(&layout::eh_stack_range().into())?;
     page_table.map_data(&stack_range().into())?;
     page_table.map_code(&layout::text_range().into())?;
     page_table.map_rodata(&layout::rodata_range().into())?;
-    page_table.map_data_dbm(&appended_payload_range().into())?;
+    page_table.map_data_dbm(&layout::image_footer_range().into())?;
     if let Err(e) = page_table.map_device(&layout::console_uart_page().into()) {
         error!("Failed to remap the UART as a dynamic page table entry: {e}");
         return Err(e);
diff --git a/guest/rialto/src/main.rs b/guest/rialto/src/main.rs
index ec26e0f..61e9948 100644
--- a/guest/rialto/src/main.rs
+++ b/guest/rialto/src/main.rs
@@ -73,7 +73,8 @@
 fn new_page_table() -> Result<PageTable> {
     let mut page_table = PageTable::default();
 
-    page_table.map_data(&layout::scratch_range().into())?;
+    page_table.map_data(&layout::data_bss_range().into())?;
+    page_table.map_data(&layout::eh_stack_range().into())?;
     page_table.map_data(&layout::stack_range(40 * PAGE_SIZE).into())?;
     page_table.map_code(&layout::text_range().into())?;
     page_table.map_rodata(&layout::rodata_range().into())?;
diff --git a/guest/vmbase_example/src/main.rs b/guest/vmbase_example/src/main.rs
index c7ef061..f00effa 100644
--- a/guest/vmbase_example/src/main.rs
+++ b/guest/vmbase_example/src/main.rs
@@ -37,7 +37,10 @@
     bionic, configure_heap,
     fdt::pci::PciInfo,
     generate_image_header,
-    layout::{console_uart_page, crosvm::FDT_MAX_SIZE, rodata_range, scratch_range, text_range},
+    layout::{
+        console_uart_page, crosvm::FDT_MAX_SIZE, data_bss_range, eh_stack_range, rodata_range,
+        text_range,
+    },
     linker, logger, main,
     memory::{PageTable, SIZE_64KB},
 };
@@ -54,7 +57,8 @@
     page_table.map_device(&console_uart_page().into())?;
     page_table.map_code(&text_range().into())?;
     page_table.map_rodata(&rodata_range().into())?;
-    page_table.map_data(&scratch_range().into())?;
+    page_table.map_data(&data_bss_range().into())?;
+    page_table.map_data(&eh_stack_range().into())?;
     page_table.map_data(&boot_stack_range().into())?;
 
     info!("Activating IdMap...");
diff --git a/libs/libcompos_common/compos_client.rs b/libs/libcompos_common/compos_client.rs
index 316eaa9..6872582 100644
--- a/libs/libcompos_common/compos_client.rs
+++ b/libs/libcompos_common/compos_client.rs
@@ -58,6 +58,8 @@
 pub struct VmParameters {
     /// The name of VM for identifying.
     pub name: String,
+    /// The OS of VM.
+    pub os: String,
     /// Whether the VM should be debuggable.
     pub debug_mode: bool,
     /// CPU topology of the VM. Defaults to 1 vCPU.
@@ -129,6 +131,7 @@
 
         let config = VirtualMachineConfig::AppConfig(VirtualMachineAppConfig {
             name: parameters.name.clone(),
+            osName: parameters.os.clone(),
             apk: Some(apk_fd),
             idsig: Some(idsig_fd),
             instanceId: instance_id,
diff --git a/libs/libvmbase/sections.ld b/libs/libvmbase/sections.ld
index 5ca5ff4..222edae 100644
--- a/libs/libvmbase/sections.ld
+++ b/libs/libvmbase/sections.ld
@@ -56,17 +56,6 @@
 	} >image
 	rodata_end = .;
 
-	.eh_stack (NOLOAD) : ALIGN(4096) {
-		/*
-		 * Get stack overflow guard from the previous page being from
-		 * .rodata and mapped read-only or left unmapped.
-		 */
-		eh_stack_limit = .;
-		. += 4096;
-		. = ALIGN(4096);
-		init_eh_stack_pointer = .;
-	} >writable_data
-
 	/*
 	 * Collect together the read-write data including .bss at the end which
 	 * will be zero'd by the entry code. This is page aligned so it can be
@@ -87,6 +76,13 @@
 	/* Everything beyond this point will not be included in the binary. */
 	bin_end = data_lma + SIZEOF(.data);
 
+	/* Data may be appended at load time to our binary. */
+	.image_footer (NOLOAD) : ALIGN(4096) {
+		image_footer_begin = .;
+		. = ALIGN(LENGTH(image));
+		image_footer_end = .;
+	} >image
+
 	/* The entry point code assumes that .bss is 16-byte aligned. */
 	.bss : ALIGN(16)  {
 		bss_begin = .;
@@ -96,6 +92,18 @@
 		bss_end = .;
 	} >writable_data
 
+	/* Left unmapped, to catch overflows of the exception handler stack. */
+	.eh_stack_guard_page (NOLOAD) : ALIGN(4096) {
+		. += 4096;
+	} >writable_data
+
+	/* Exception handler stack, mapped read-write. */
+	.eh_stack (NOLOAD) : ALIGN(4096) {
+		eh_stack_limit = .;
+		. += 4096;
+		init_eh_stack_pointer = .;
+	} >writable_data
+
 	/* Left unmapped, to catch overflows of the stack. */
 	.stack_guard_page (NOLOAD) : ALIGN(4096) {
 		. += 4096;
diff --git a/libs/libvmbase/src/layout.rs b/libs/libvmbase/src/layout.rs
index adcb2fa..a8f7827 100644
--- a/libs/libvmbase/src/layout.rs
+++ b/libs/libvmbase/src/layout.rs
@@ -70,6 +70,11 @@
     linker_region!(rodata_begin, rodata_end)
 }
 
+/// Region which may contain a footer appended to the binary at load time.
+pub fn image_footer_range() -> Range<VirtualAddress> {
+    linker_region!(image_footer_begin, image_footer_end)
+}
+
 /// Initialised writable data.
 pub fn data_range() -> Range<VirtualAddress> {
     linker_region!(data_begin, data_end)
@@ -80,6 +85,11 @@
     linker_region!(bss_begin, bss_end)
 }
 
+/// Writable data region for .data and .bss.
+pub fn data_bss_range() -> Range<VirtualAddress> {
+    linker_region!(data_begin, bss_end)
+}
+
 /// Writable data region for the stack.
 pub fn stack_range(stack_size: usize) -> Range<VirtualAddress> {
     let end = linker_addr!(init_stack_pointer);
@@ -89,9 +99,9 @@
     start..end
 }
 
-/// All writable sections, excluding the stack.
-pub fn scratch_range() -> Range<VirtualAddress> {
-    linker_region!(eh_stack_limit, bss_end)
+/// Writable data region for the exception handler stack.
+pub fn eh_stack_range() -> Range<VirtualAddress> {
+    linker_region!(eh_stack_limit, init_eh_stack_pointer)
 }
 
 /// Range of the page at UART_PAGE_ADDR of PAGE_SIZE.
diff --git a/libs/libvmbase/src/linker.rs b/libs/libvmbase/src/linker.rs
index 97bef3f..8654cf9 100644
--- a/libs/libvmbase/src/linker.rs
+++ b/libs/libvmbase/src/linker.rs
@@ -35,6 +35,12 @@
     pub static dtb_end: u8;
     /// First byte of the region available for the exception handler stack.
     pub static eh_stack_limit: u8;
+    /// First byte of the `.image_footer` section.
+    pub static image_footer_begin: u8;
+    /// First byte beyond the `.image_footer` section.
+    pub static image_footer_end: u8;
+    /// First byte past the region available for the exception handler stack.
+    pub static init_eh_stack_pointer: u8;
     /// First byte past the region available for the stack.
     pub static init_stack_pointer: u8;
     /// First byte of the `.rodata` section.