Add support for aarch64 builds

* Requires clients to install qemu-user-static.
* Requires setting multiarch/qemu-user-static on podman.
* Uses non-sysroot based build for aarch64.
* Adds flags to select architecture, defaults to x86_64.
* Based on exploratory change from plabatut@.

Bug: 331635690
Test: Verified container build of x86_64, aarch64.
Test: Verified launch of resulting QEMU binary on ARM64 host.
Test: Verified qemu/scripts/check.sh.
Change-Id: I770210e5145e95f468ab0dfff72dff5e9e94910f

4 files changed, 242 insertions, 58 deletions

diff --git a/qemu/manifest.xml b/qemu/manifest.xml
index 602cdcf..55c465b 100644
--- a/qemu/manifest.xml
+++ b/qemu/manifest.xml
@@ -65,4 +65,4 @@
   <project path="qemu/third_party/rust/crates/zerocopy" name="platform/external/rust/crates/zerocopy" revision="738d78f6696da049502fc4436a70ca8799e1569e" />
   <project path="qemu/third_party/rust/crates/zerocopy-derive" name="platform/external/rust/crates/zerocopy-derive" revision="e31ff4fde30f2bef09ae8f20b93d57b9040c7c1c" />
   <project path="qemu/third_party/zlib" name="platform/external/zlib" revision="81774276a9cbf47177a1b7555bb6e3ec73bdcd25" />
-</manifest>
\ No newline at end of file
+</manifest>
diff --git a/qemu/scripts/genrepo.py b/qemu/scripts/genrepo.py
index 0884c0c..004a0fd 100644
--- a/qemu/scripts/genrepo.py
+++ b/qemu/scripts/genrepo.py
@@ -287,6 +287,12 @@ def GenerateRepoManifest(projects, out):
       ET.SubElement(elem, "linkfile", src=".", dest=linkat)
 
   tree = ET.ElementTree(manifest)
+  tree.getroot().insert(
+      0,
+      ET.Comment(
+          "DO NOT EDIT. This file is generated by " + os.path.basename(__file__)
+      ),
+  )
   ET.indent(tree)
   tree.write(out, encoding="unicode")
 
diff --git a/qemu/scripts/rebuild.py b/qemu/scripts/rebuild.py
index df4d714..54e972a 100755
--- a/qemu/scripts/rebuild.py
+++ b/qemu/scripts/rebuild.py
@@ -15,6 +15,7 @@
 """A script to rebuild QEMU from scratch on Linux."""
 
 import argparse
+from enum import Enum
 import os
 from pathlib import Path
 import shlex
@@ -28,6 +29,11 @@ from typing import List
 from typing import Sequence
 
 
+class Architecture(Enum):
+  AARCH64 = "aarch64"
+  X86_64 = "x86_64"
+
+
 def copy_file(src: Path, dst: Path) -> None:
   log("  COPY_FILE %s --> %s" % (src, dst))
   os.makedirs(dst.parent, exist_ok=True)
@@ -39,36 +45,69 @@ def log(msg: str) -> None:
 
 
 def create_dev_environment(
-    build_dir: Path, install_dir: Path, prebuilts_dir: Path, clang_dir: Path
+    build_dir: Path,
+    install_dir: Path,
+    prebuilts_dir: Path,
+    clang_dir: Path,
+    target_arch: Architecture,
 ) -> Dict[str, str]:
   sysroot = str(build_dir / "sysroot")
   binprefix = "%s/" % (clang_dir / "bin")
   env = os.environ.copy()
   path = env["PATH"]
   ld_library_path = env.get("LD_LIBRARY_PATH", "")
-  env.update({
-      "CC": f"{binprefix}clang --sysroot={sysroot}",
-      "CXX": f"{binprefix}clang++ --sysroot={sysroot} -stdlib=libc++",
-      # FIXME: this file does not exist.
-      "LD": f"{binprefix}llvm-ld --sysroot={sysroot}",
-      "AR": f"{binprefix}llvm-ar",
-      "NM": f"{binprefix}llvm-nm",
-      "PKG_CONFIG_PATH": ":".join([
-          f"{install_dir}/usr/lib/x86_64-linux-gnu/pkgconfig",
-          f"{install_dir}/usr/lib/pkgconfig",
-          f"{sysroot}/usr/lib/pkgconfig",
-      ]),
-      "PATH": f"{install_dir}/usr/bin:{path}",
-      "LD_LIBRARY_PATH": ":".join([
-          f"{install_dir}/usr/lib/x86_64-linux-gnu",
-          f"{install_dir}/usr/lib",
-          f"{clang_dir}/lib:{ld_library_path}",
-      ]),
-      # Required to ensure that configure scripts that do not rely
-      # on pkg-config find their dependencies properly.
-      "CFLAGS": f"-I{install_dir}/usr/include",
-      "LDFLAGS": f"-Wl,-L{install_dir}/usr/lib",
-  })
+
+  if target_arch == Architecture.AARCH64:
+    cargo_path = Path(env["HOME"]) / ".cargo" / "bin"
+    env.update({
+        "CC": f"clang",
+        "CXX": f"clang++ -stdlib=libc++",
+        # FIXME: this file does not exist.
+        "LD": f"llvm-ld",
+        "AR": f"llvm-ar",
+        "NM": f"llvm-nm",
+        "PKG_CONFIG_PATH": ":".join([
+            f"{install_dir}/usr/lib/aarch64-linux-gnu/pkgconfig",
+            f"{install_dir}/usr/lib/pkgconfig",
+        ]),
+        "PATH": f"{cargo_path}:{install_dir}/usr/bin:{path}",
+        "LD_LIBRARY_PATH": ":".join([
+            f"{install_dir}/usr/lib/aarch64-linux-gnu",
+            f"{install_dir}/usr/lib",
+            f"{ld_library_path}",
+        ]),
+        # Required to ensure that configure scripts that do not rely
+        # on pkg-config find their dependencies properly.
+        "CFLAGS": f"-I{install_dir}/usr/include",
+        "CXXFLAGS": f"-I{install_dir}/usr/include",
+        "LDFLAGS": f"-Wl,-L{install_dir}/usr/lib",
+    })
+  else:
+    env.update({
+        "CC": f"{binprefix}clang --sysroot={sysroot}",
+        "CXX": f"{binprefix}clang++ --sysroot={sysroot} -stdlib=libc++",
+        # FIXME: this file does not exist.
+        "LD": f"{binprefix}llvm-ld --sysroot={sysroot}",
+        "AR": f"{binprefix}llvm-ar",
+        "NM": f"{binprefix}llvm-nm",
+        "PKG_CONFIG_PATH": ":".join([
+            f"{install_dir}/usr/lib/x86_64-linux-gnu/pkgconfig",
+            f"{install_dir}/usr/lib/pkgconfig",
+            f"{install_dir}/usr/lib64/pkgconfig",
+            f"{sysroot}/usr/lib/pkgconfig",
+        ]),
+        "PATH": f"{install_dir}/usr/bin:{path}",
+        "LD_LIBRARY_PATH": ":".join([
+            f"{install_dir}/usr/lib/x86_64-linux-gnu",
+            f"{install_dir}/usr/lib",
+            f"{clang_dir}/lib:{ld_library_path}",
+        ]),
+        # Required to ensure that configure scripts that do not rely
+        # on pkg-config find their dependencies properly.
+        "CFLAGS": f"-I{install_dir}/usr/include",
+        "CXXFLAGS": f"-I{install_dir}/usr/include",
+        "LDFLAGS": f"-Wl,-L{install_dir}/usr/lib",
+    })
   return env
 
 
@@ -161,7 +200,8 @@ class BuildConfig(object):
         or running commands.
   """
 
-  def __init__(self, build_dir: Path, top_dir: Path):
+  def __init__(self, build_dir: Path, top_dir: Path, target_arch: Architecture):
+    self._target_arch = target_arch
     self._build_dir = build_dir
     self._sysroot_dir = build_dir / "sysroot"
     self._install_dir = build_dir / "dest-install"
@@ -173,6 +213,7 @@ class BuildConfig(object):
         self._install_dir,
         self._prebuilts_dir,
         self._clang_dir,
+        self._target_arch,
     )
 
     # By default, run commands directly. Subclasses can override
@@ -185,6 +226,10 @@ class BuildConfig(object):
       self._env[varname] = "ccache " + self._env[varname]
 
   @property
+  def target_arch(self) -> Architecture:
+    return self._target_arch
+
+  @property
   def build_dir(self) -> Path:
     return self._build_dir
 
@@ -350,6 +395,10 @@ project = Project()
 
 @project.task([])
 def build_task_for_sysroot(build: BuildConfig):
+  if build.target_arch == Architecture.AARCH64:
+    # We don't build the sysroot for AARCH64 or its dependencies.
+    return
+
   # populate_sysroot(build.build_dir / 'sysroot', build.prebuilts_dir),
   dst_sysroot = build.build_dir / "sysroot"
   dst_sysroot_lib_dir = dst_sysroot / "usr" / "lib"
@@ -380,6 +429,10 @@ def build_task_for_sysroot(build: BuildConfig):
 
 @project.task([build_task_for_sysroot])
 def build_task_for_ninja(build: BuildConfig):
+  if build.target_arch == Architecture.AARCH64:
+    # We use apt to install ninja.
+    return
+
   build.copy_file(
       build.prebuilts_dir / "ninja" / "ninja",
       build.install_dir / "usr" / "bin" / "ninja",
@@ -388,6 +441,10 @@ def build_task_for_ninja(build: BuildConfig):
 
 @project.task([])
 def build_task_for_python(build: BuildConfig):
+  if build.target_arch == Architecture.AARCH64:
+    # We use apt to install python3.10.
+    return
+
   src_python_dir = build.third_party_dir / "python"
   dst_python_dir = build.install_dir / "usr"
   for d in ("bin", "lib", "share"):
@@ -401,11 +458,13 @@ def build_task_for_meson(build: BuildConfig):
   meson_packager = (
       build.third_party_dir / "meson" / "packaging" / "create_zipapp.py"
   )
+  usr_bin = build.install_dir / "usr" / "bin"
+  build.run(["mkdir", "-p", usr_bin], env=None)
   build.run([
       "python3",
       "-S",
       meson_packager,
-      "--outfile=%s" % (build.install_dir / "usr" / "bin" / "meson"),
+      "--outfile=%s" % (usr_bin / "meson"),
       "--interpreter",
       "/usr/bin/env python3",
       build.third_party_dir / "meson",
@@ -414,7 +473,14 @@ def build_task_for_meson(build: BuildConfig):
 
 @project.task([])
 def build_task_for_rust(build: BuildConfig):
-  log("Install prebuilt rust.")
+  if build.target_arch == Architecture.AARCH64:
+    # We use rustup to install rust, but we need the following libraries
+    # for the aarch64 portable build.
+    dst_dir = build.install_dir / "usr" / "lib64"
+    for lib in ["libc++.so.1", "libc++abi.so.1", "libunwind.so.1"]:
+      build.copy_file(Path(f"/lib/aarch64-linux-gnu/{lib}"), dst_dir / lib)
+    return
+
   src_rust_dir = build.prebuilts_dir / "rust" / "linux-x86" / "1.73.0"
   dst_rust_dir = build.install_dir / "usr"
   for d in ("bin", "lib", "lib64", "share"):
@@ -430,6 +496,10 @@ def build_task_for_rust(build: BuildConfig):
 
 @project.task([build_task_for_sysroot])
 def build_task_for_make(build: BuildConfig) -> None:
+  if build.target_arch == Architecture.AARCH64:
+    # We use apt to install make.
+    return
+
   build.copy_file(
       build.prebuilts_dir / "build-tools" / "linux-x86" / "bin" / "make",
       build.install_dir / "usr" / "bin" / "make",
@@ -438,7 +508,10 @@ def build_task_for_make(build: BuildConfig) -> None:
 
 @project.task([])
 def build_task_for_cmake(build: BuildConfig):
-  log("Install Cmake prebuilt.")
+  if build.target_arch == Architecture.AARCH64:
+    # We use apt to install cmake.
+    return
+
   build.copy_file(
       build.prebuilts_dir / "cmake" / "bin" / "cmake",
       build.install_dir / "usr" / "bin" / "cmake",
@@ -806,8 +879,12 @@ def build_task_for_libdrm(build: BuildConfig):
   )
 
 
-@project.task([])
+@project.task([build_task_for_sysroot])
 def build_task_for_egl(build: BuildConfig):
+  if build.target_arch == Architecture.AARCH64:
+    # We use apt to install the EGL headers.
+    return
+
   build.copy_dir(
       build.third_party_dir / "egl" / "api" / "KHR",
       build.sysroot_dir / "usr" / "include" / "KHR",
@@ -862,23 +939,35 @@ def build_task_for_gfxstream(build: BuildConfig):
 def build_task_for_rutabaga(build: BuildConfig):
   out_dir = build.make_subdir(Path("rutabaga"))
   cmd_args = [
-      build.install_dir / "usr/bin/cargo",
+      "cargo",
       "build",
       "--offline",
       "--features=gfxstream",
       "--release",
   ]
-  env = {
-      "CARGO_TARGET_DIR": str(out_dir),
-      "GFXSTREAM_PATH": str(build.build_dir / "gfxstream" / "host"),
-      "PATH": f"{build.install_dir}/usr/bin:{os.environ['PATH']}",
-      "CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_LINKER": (
-          f"{build.clang_dir}/bin/clang"
-      ),
-      "RUSTFLAGS": (
-          f"-Clink-arg=--sysroot={build.sysroot_dir} -Clink-arg=-Wl,-rpath,$ORIGIN"
-      ),
-  }
+  if build.target_arch == Architecture.AARCH64:
+    cargo_path = Path(os.environ["HOME"]) / ".cargo" / "bin"
+    env = {
+        "CARGO_TARGET_DIR": str(out_dir),
+        "GFXSTREAM_PATH": str(build.build_dir / "gfxstream" / "host"),
+        "PATH": (
+            f"{cargo_path}:{build.install_dir}/usr/bin:{os.environ['PATH']}"
+        ),
+        "CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_LINKER": "clang",
+        "RUSTFLAGS": f"-Clink-arg=-Wl,-rpath,$ORIGIN",
+    }
+  else:
+    env = {
+        "CARGO_TARGET_DIR": str(out_dir),
+        "GFXSTREAM_PATH": str(build.build_dir / "gfxstream" / "host"),
+        "PATH": f"{build.install_dir}/usr/bin:{os.environ['PATH']}",
+        "CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_LINKER": (
+            f"{build.clang_dir}/bin/clang"
+        ),
+        "RUSTFLAGS": (
+            f"-Clink-arg=--sysroot={build.sysroot_dir} -Clink-arg=-Wl,-rpath,$ORIGIN"
+        ),
+    }
   rutabaga_src_dir = build.third_party_dir / "crosvm" / "rutabaga_gfx" / "ffi"
   build.run(cmd_args, rutabaga_src_dir, env)
 
@@ -889,7 +978,7 @@ def build_task_for_rutabaga(build: BuildConfig):
   build.run(
       ["ln", "-sf", "librutabaga_gfx_ffi.so", "librutabaga_gfx_ffi.so.0"],
       build.install_dir / "usr" / "lib",
-      env={}
+      env={},
   )
   build.copy_file(
       out_dir / "release" / "rutabaga_gfx_ffi.pc",
@@ -910,22 +999,24 @@ def build_task_for_libgbm(build: BuildConfig):
   # gbm is part of mesa which is a large project.
   # The dependency is taken fron the system.
   build.copy_file(
-      "/usr/lib/x86_64-linux-gnu/libgbm.so.1",
+      Path(f"/usr/lib/{build.target_arch.value}-linux-gnu/libgbm.so.1"),
       build.install_dir / "usr/lib/libgbm.so.1",
   )
   build.copy_file(
-      "/usr/lib/x86_64-linux-gnu/libgbm.so",
+      Path(f"/usr/lib/{build.target_arch.value}-linux-gnu/libgbm.so"),
       build.install_dir / "usr/lib/libgbm.so",
   )
   build.copy_file(
-      "/usr/lib/x86_64-linux-gnu/libgbm.so.1.0.0",
+      Path(f"/usr/lib/{build.target_arch.value}-linux-gnu/libgbm.so.1.0.0"),
       build.install_dir / "usr/lib/libgbm.so.1.0.0",
   )
   build.copy_file(
-      "/usr/lib/x86_64-linux-gnu/pkgconfig/gbm.pc",
+      Path(f"/usr/lib/{build.target_arch.value}-linux-gnu/pkgconfig/gbm.pc"),
       build.install_dir / "usr/lib/pkgconfig/gbm.pc",
   )
-  build.copy_file("/usr/include/gbm.h", build.install_dir / "usr/include/gbm.h")
+  build.copy_file(
+      Path("/usr/include/gbm.h"), build.install_dir / "usr/include/gbm.h"
+  )
 
 
 @project.task([
@@ -993,11 +1084,38 @@ def build_task_for_virglrenderer(build: BuildConfig):
 
 
 @project.task([
+    build_task_for_meson,
+    build_task_for_ninja,
+])
+def build_task_for_dtc(build: BuildConfig):
+  src_dir = build.third_party_dir / "dtc"
+  build_dir = build.make_subdir(Path("dtc"))
+  build.run(
+      [
+          "meson",
+          "setup",
+          "--prefix=%s/usr" % build.install_dir,
+          "--libdir=%s/usr/lib" % build.install_dir,
+          # Option taken from qemu/meson.build subproject dtc.
+          "-Dtools=false",
+          "-Dyaml=disabled",
+          "-Dpython=disabled",
+          "-Ddefault_library=static",
+          build_dir,
+          src_dir,
+      ],
+  )
+
+  build.run(["ninja", "install"], build_dir)
+
+
+@project.task([
     build_task_for_make,
     build_task_for_libslirp,
     build_task_for_glib,
     build_task_for_pixman,
     build_task_for_zlib,
+    build_task_for_dtc,
     build_task_for_pkg_config,
     build_task_for_rutabaga,
     build_task_for_gfxstream,
@@ -1011,12 +1129,33 @@ def build_task_for_qemu(build: BuildConfig):
   ]
   src_dir = build.third_party_dir / "qemu"
   build_dir = build.make_subdir(Path("qemu"))
+
+  # Copy third-pary projects to qemu/subprojects directory so that meson does
+  # not try to checkout those sources with git.
+  for name in ("keycodemapdb", "berkeley-softfloat-3", "berkeley-testfloat-3"):
+    subproject = src_dir / "subprojects" / name
+    build.run(["rm", "-rf", src_dir / "subprojects" / name], env={})
+    build.run(
+        ["cp", "-r", build.third_party_dir / name, src_dir / "subprojects"],
+        env={},
+    )
+    # Add project files to the sources.
+    packagefiles = src_dir / "subprojects" / "packagefiles" / name
+    for package_file in packagefiles.glob("*"):
+      build.run(
+          ["cp", package_file, subproject],
+          env={},
+      )
+
   cmd_args: List[str | Path] = [
       src_dir.resolve() / "configure",
       "--prefix=/usr",
       "--target-list=%s" % ",".join(target_list),
       "--disable-plugins",
       "--enable-virglrenderer",
+      # Disable source checkout of missing dependencies, so that
+      # missing project chan be found early .
+      "--disable-download",
       # Cuttlefish is packaged in host archives that are assembled in
       # `$ANDROID_BUILD_TOP/out/host/linux-x86`.
       # Binaries are in `./bin` and resources are in `./usr/share` which is
@@ -1056,11 +1195,18 @@ def build_task_for_qemu_portable(build: BuildConfig):
       "dest-install/usr/lib/librutabaga_gfx_ffi.so.0",
       "dest-install/usr/lib64/libc++.so.1",
   ]
+  if build.target_arch == Architecture.AARCH64:
+    files += [
+        "dest-install/usr/lib64/libc++abi.so.1",
+        "dest-install/usr/lib64/libunwind.so.1",
+    ]
+
   # Meson install directory depends on the system and differs between podman and
   # the developer's workstation. Probe the file system to pick the right location.
   either_or = [
-      "dest-install/usr/lib/x86_64-linux-gnu/libgfxstream_backend.so.0",
+      f"dest-install/usr/lib/{build.target_arch}-linux-gnu/libgfxstream_backend.so.0",
       "dest-install/usr/lib/libgfxstream_backend.so.0",
+      "dest-install/usr/lib64/libgfxstream_backend.so.0",
   ]
   try:
     files.append(
@@ -1105,6 +1251,13 @@ def build_task_for_qemu_test(build: BuildConfig):
 
 def main() -> int:
   parser = argparse.ArgumentParser(description=__doc__)
+  parser.add_argument(
+      "--arch",
+      type=Architecture,
+      choices=list(Architecture),
+      default=Architecture.X86_64,
+      help="Target architecture.",
+  )
   parser.add_argument("--build-dir", required=True, help="Build directory.")
   parser.add_argument("--ccache", action="store_true", help="Enable ccache.")
   parser.add_argument(
@@ -1124,7 +1277,7 @@ def main() -> int:
   build_dir = Path(args.build_dir)
 
   top_dir = Path(os.path.dirname(__file__)).parent
-  build_config = BuildConfig(build_dir, top_dir)
+  build_config = BuildConfig(build_dir, top_dir, args.arch)
 
   if args.ccache:
     build_config.enable_ccache()
diff --git a/qemu/scripts/rebuild_in_container.sh b/qemu/scripts/rebuild_in_container.sh
index a381736..66acd3d 100755
--- a/qemu/scripts/rebuild_in_container.sh
+++ b/qemu/scripts/rebuild_in_container.sh
@@ -2,10 +2,15 @@
 # Starts an isolated build in a container
 set -e
 
+ARCH="x86_64"
 FROM_EXISTING_SOURCES=0
 
 while [[ $# -gt 0 ]]; do
   case $1 in
+    --arch)
+      ARCH="$2"
+      shift 2
+      ;;
     --from_existing_sources)
       FROM_EXISTING_SOURCES=1
       shift
@@ -13,7 +18,7 @@ while [[ $# -gt 0 ]]; do
     *)
       echo "Build QEMU from sources in a container."
       echo
-      echo "usage: $0 [--from_existing_sources]"
+      echo "usage: $0 [--from_existing_sources] [--arch x86_64|aarch64]"
       echo
       echo "Options:"
       echo "  --from_existing_sources: Do not checkout sources with repo,"
@@ -37,18 +42,34 @@ if [ "$FROM_EXISTING_SOURCES" -eq 0 ]; then
   echo "Check out sources with repo at: ${SRC_DIR}"
   rm -rf "${SRC_DIR}"
   mkdir -p "${SRC_DIR}"
+  cd "${SRC_DIR}"
   repo init --manifest-url "${GIT_ROOT}" \
     --manifest-name=qemu/manifest.xml
 
   repo sync
 else
-  echo "Reuse existing source checkout at: ${SRC_DIR}"
   readonly SRC_DIR="$GIT_ROOT"
+  echo "Reuse existing source checkout at: ${SRC_DIR}"
+fi
+
+readonly COMMON_APT_PACKAGES="autoconf libgbm-dev libtool texinfo"
+readonly AARCH64_APT_PACKAGES="clang cmake curl libc++-dev libc++abi-dev \
+  libegl-dev libgcc-12-dev libxml2-utils llvm make ninja-build \
+  patchelf pkg-config python3 python3-distutils python3-venv"
+
+APT_PACKAGES="${COMMON_APT_PACKAGES}"
+RUSTUP_COMMAND=":"
+PYTHON_BIN="/src/qemu/third_party/python/bin/python3"
+if [[ "$ARCH" == "aarch64" ]]; then
+  APT_PACKAGES="${APT_PACKAGES} ${AARCH64_APT_PACKAGES}"
+  RUSTUP_COMMAND="curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -q -y"
+  PYTHON_BIN="python3"
 fi
 
 readonly COMMAND="apt-get update && \
-apt-get -qy install autoconf libtool texinfo libgbm-dev && \
-/src/qemu/third_party/python/bin/python3 /src/qemu/scripts/rebuild.py --build-dir /out"
+apt-get -qy install ${APT_PACKAGES} && \
+${RUSTUP_COMMAND} && \
+${PYTHON_BIN} /src/qemu/scripts/rebuild.py --arch ${ARCH} --build-dir /out"
 
 # Note: `/src` is mounted with a file overlay so that cargo can write
 # `third_party/crossvm/rutabaga_gfx/ffi/Cargo.lock` file. We didn't find
@@ -59,16 +80,20 @@ podman run --name qemu-build \
     --pids-limit=-1 \
     --volume "${SRC_DIR}:/src:O" \
     --volume "${WORK_DIR}:/out" \
-    docker.io/debian:11-slim \
+    --arch ${ARCH} \
+    docker.io/debian:12-slim \
     bash -c "${COMMAND}"
 
+# Tip: Use `--interactive`, `--tty` and
+# `bash -c "${COMMAND};$SHELL"` for interactive debug.
+
 if [ "$FROM_EXISTING_SOURCES" -eq 0 ]; then
-  readonly DEST="${GIT_ROOT}/qemu/x86_64-linux-gnu"
-  echo "Overwrite prebuild at: ${DEST}"
+  readonly DEST="${GIT_ROOT}/qemu/${ARCH}-linux-gnu"
+  echo "Overwrite prebuilt at: ${DEST}"
   rm -rf "${DEST}/*"
   tar -xvf "${WORK_DIR}/qemu-portable.tar.gz" -C "${DEST}"
 
 fi
 
 echo "Binary available at: ${WORK_DIR}/qemu-portable/bin"
-echo "Done."
\ No newline at end of file
+echo "Done."