Compress arm64 GKI with lz4
Now that crosvm can use lz4-compressed kernel, this change compresses
microdroid kernels with lz4 to reduce bloating of virt apex.
* virt apex size becomes from 101MB to 84MB.
* MicrodroidBenchmarks shows that there is no performance regression.
Bug: 315141974
Test: atest MicrodroidTests MicrodroidHostTests
Test: run MicrodroidBenchmarks and compare metrics
Change-Id: I59e40340260ef89d9e116f7e050fa4f30efb0d3e
diff --git a/apex/Android.bp b/apex/Android.bp
index f2badfa..4586f51 100644
--- a/apex/Android.bp
+++ b/apex/Android.bp
@@ -255,6 +255,7 @@
"initrd_bootconfig",
"lpmake",
"lpunpack",
+ "lz4",
"simg2img",
],
}
@@ -275,6 +276,7 @@
"initrd_bootconfig",
"lpmake",
"lpunpack",
+ "lz4",
"sign_virt_apex",
"simg2img",
],
diff --git a/apex/sign_virt_apex.py b/apex/sign_virt_apex.py
index 0b6137b..fbbd152 100644
--- a/apex/sign_virt_apex.py
+++ b/apex/sign_virt_apex.py
@@ -153,12 +153,18 @@
'--key', key, '--output', output])
+def is_lz4(args, path):
+ # error 44: Unrecognized header
+ result = RunCommand(args, ['lz4', '-t', path], expected_return_values={0, 44})
+ return result[1] == 0
+
+
def AvbInfo(args, image_path):
"""Parses avbtool --info image output
Args:
args: program arguments.
- image_path: The path to the image.
+ image_path: The path to the image, either raw or lz4 compressed
descriptor_name: Descriptor name of interest.
Returns:
@@ -169,6 +175,11 @@
if not os.path.exists(image_path):
raise ValueError(f'Failed to find image: {image_path}')
+ if is_lz4(args, image_path):
+ with tempfile.NamedTemporaryFile() as decompressed_image:
+ RunCommand(args, ['lz4', '-d', '-f', image_path, decompressed_image.name])
+ return AvbInfo(args, decompressed_image.name)
+
output, ret_code = RunCommand(
args, ['avbtool', 'info_image', '--image', image_path], expected_return_values={0, 1})
if ret_code == 1:
@@ -560,11 +571,7 @@
wait=[vbmeta_f])
# Re-sign kernel. Note kernel's vbmeta contain addition descriptor from ramdisk(s)
- def resign_kernel(kernel, initrd_normal, initrd_debug):
- kernel_file = files[kernel]
- initrd_normal_file = files[initrd_normal]
- initrd_debug_file = files[initrd_debug]
-
+ def resign_decompressed_kernel(kernel_file, initrd_normal_file, initrd_debug_file):
_, kernel_image_descriptors = AvbInfo(args, kernel_file)
salts = extract_hash_descriptors(
kernel_image_descriptors, lambda descriptor: descriptor['Salt'])
@@ -580,6 +587,27 @@
additional_images=[initrd_normal_hashdesc, initrd_debug_hashdesc],
wait=[initrd_n_f, initrd_d_f])
+ def resign_compressed_kernel(kernel_file, initrd_normal_file, initrd_debug_file):
+ # decompress, re-sign, compress again
+ with tempfile.TemporaryDirectory() as work_dir:
+ decompressed_kernel_file = os.path.join(work_dir, os.path.basename(kernel_file))
+ RunCommand(args, ['lz4', '-d', kernel_file, decompressed_kernel_file])
+ resign_decompressed_kernel(decompressed_kernel_file, initrd_normal_file,
+ initrd_debug_file).result()
+ RunCommand(args, ['lz4', '-9', '-f', decompressed_kernel_file, kernel_file])
+
+ def resign_kernel(kernel, initrd_normal, initrd_debug):
+ kernel_file = files[kernel]
+ initrd_normal_file = files[initrd_normal]
+ initrd_debug_file = files[initrd_debug]
+
+ # kernel may be compressed with lz4.
+ if is_lz4(args, kernel_file):
+ return Async(resign_compressed_kernel, kernel_file, initrd_normal_file,
+ initrd_debug_file)
+ else:
+ return resign_decompressed_kernel(kernel_file, initrd_normal_file, initrd_debug_file)
+
_, original_kernel_descriptors = AvbInfo(args, files['kernel'])
resign_kernel_task = resign_kernel('kernel', 'initrd_normal.img', 'initrd_debuggable.img')