kleaf: kernel_prebuilt_repo specifies kernel_filegroup

After this change, usually, @gki_prebuilts//kernel_aarch64
points to the kernel_filegroup.

This target replaces the @kleaf//common:kernel_aarch64_downloaded_or_build
targets. The targets in @kleaf//common requires the
following declaration in MODULE.bazel to work:

  use_repo(kernel_prebuilt_ext, "gki_prebuilts")

However, per design, the name "gki_prebuilts" is defined
by the MODULE.bazel of the root module (the Bazel module
that holds the DDK drivers), and it does not need to have
this specific name. Hence, move the target to @gki_prebuilts
so the root module can use the @gki_prebuilts//kernel_aarch64
target directly.

Test: TH
Bug: 291918087
Change-Id: If93827580a2d70bf68dee1f787477034ecfd0b6c

2 files changed, 48 insertions, 0 deletions

diff --git a/kleaf/impl/kernel_prebuilt_repo.bzl b/kleaf/impl/kernel_prebuilt_repo.bzl
index 38b4ce0..6882752 100644
--- a/kleaf/impl/kernel_prebuilt_repo.bzl
+++ b/kleaf/impl/kernel_prebuilt_repo.bzl
@@ -15,6 +15,11 @@
 """Repository for kernel prebuilts."""
 
 load(
+    ":constants.bzl",
+    "FILEGROUP_DEF_ARCHIVE_SUFFIX",
+    "FILEGROUP_DEF_TEMPLATE_NAME",
+)
+load(
     ":kernel_prebuilt_utils.bzl",
     "CI_TARGET_MAPPING",
     "GKI_DOWNLOAD_CONFIGS",
@@ -254,10 +259,51 @@ filegroup(
         )
         repository_ctx.file(_join(local_filename, "BUILD.bazel"), content)
 
+    _create_top_level_files(repository_ctx, download_config)
+
+def _create_top_level_files(repository_ctx, download_config):
+    bazel_target_name = repository_ctx.attr.target
     repository_ctx.file("""WORKSPACE.bazel""", """\
 workspace({})
 """.format(repr(repository_ctx.attr.name)))
 
+    filegroup_decl_archives = []
+    for local_filename in download_config:
+        if _basename(local_filename).endswith(FILEGROUP_DEF_ARCHIVE_SUFFIX):
+            local_path = repository_ctx.path(_join(local_filename, _basename(local_filename)))
+            filegroup_decl_archives.append(local_path)
+
+    if not filegroup_decl_archives:
+        return
+    if len(filegroup_decl_archives) > 1:
+        fail("Multiple files with suffix {}: {}".format(
+            FILEGROUP_DEF_ARCHIVE_SUFFIX,
+            filegroup_decl_archives,
+        ))
+
+    filegroup_decl_archive = filegroup_decl_archives[0]
+    repository_ctx.extract(
+        # If local_artifact_path is set, filegroup_decl_archive is a symlink.
+        # The symlink is under the working directory so we can't set
+        # watch_archive = "yes".
+        # Use realpath (which may point outside the working directory) and
+        # watch_archive = "auto" (the default) achieves optimal effect.
+        archive = filegroup_decl_archive.realpath,
+        output = repository_ctx.path(bazel_target_name),
+    )
+
+    template_path = repository_ctx.path(_join(bazel_target_name, FILEGROUP_DEF_TEMPLATE_NAME))
+    template_content = repository_ctx.read(template_path)
+
+    repository_ctx.file(repository_ctx.path(_join(bazel_target_name, "BUILD.bazel")), """\
+load({kernel_bzl_repr}, "kernel_filegroup")
+
+{template_content}
+""".format(
+        kernel_bzl_repr = repr(str(Label("//build/kernel/kleaf:kernel.bzl"))),
+        template_content = template_content,
+    ))
+
 kernel_prebuilt_repo = repository_rule(
     implementation = _kernel_prebuilt_repo_impl,
     attrs = {
diff --git a/kleaf/impl/kernel_prebuilt_utils.bzl b/kleaf/impl/kernel_prebuilt_utils.bzl
index 4da59e0..82028c6 100644
--- a/kleaf/impl/kernel_prebuilt_utils.bzl
+++ b/kleaf/impl/kernel_prebuilt_utils.bzl
@@ -20,6 +20,7 @@ load(
 )
 load(
     ":constants.bzl",
+    "FILEGROUP_DEF_ARCHIVE_SUFFIX",
     "GKI_ARTIFACTS_AARCH64_OUTS",
     "MODULES_STAGING_ARCHIVE",
     "MODULE_OUTS_FILE_SUFFIX",
@@ -91,6 +92,7 @@ GKI_DOWNLOAD_CONFIGS = [
     {
         "target_suffix": "ddk_artifacts",
         "outs": [
+            "kernel_aarch64" + FILEGROUP_DEF_ARCHIVE_SUFFIX,
             # TODO(b/291918087): Drop after common_kernels no longer use kernel_filegroup.
             #   These files should already be in kernel_filegroup_declaration.
             # _modules_prepare