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usr: Add support for zstd compressed initramfs

- Add support for a zstd compressed initramfs.

- Add compression for compressing built-in initramfs with zstd.

I have tested this patch by boot testing with buildroot and QEMU.
Specifically, I booted the kernel with both a zstd and gzip compressed
initramfs, both built into the kernel and separate. I ensured that the
correct compression algorithm was used. I tested on arm, aarch64, i386,
and x86_64.

This patch has been tested in production on aarch64 and x86_64 devices.

Additionally, I have performance measurements from internal use in
production. On an aarch64 device we saw 19 second boot time improvement
from switching from lzma to zstd (27 seconds to 8 seconds). On an x86_64
device we saw a 9 second boot time reduction from switching from xz to
zstd.

Signed-off-by: Nick Terrell <terrelln@fb.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20200730190841.2071656-5-nickrterrell@gmail.com
master
Nick Terrell 10 months ago
committed by Ingo Molnar
parent
commit
a30d8a39f0
2 changed files with 21 additions and 0 deletions
  1. +20
    -0
      usr/Kconfig
  2. +1
    -0
      usr/Makefile

+ 20
- 0
usr/Kconfig View File

@ -100,6 +100,15 @@ config RD_LZ4
Support loading of a LZ4 encoded initial ramdisk or cpio buffer
If unsure, say N.
config RD_ZSTD
bool "Support initial ramdisk/ramfs compressed using ZSTD"
default y
depends on BLK_DEV_INITRD
select DECOMPRESS_ZSTD
help
Support loading of a ZSTD encoded initial ramdisk or cpio buffer.
If unsure, say N.
choice
prompt "Built-in initramfs compression mode"
depends on INITRAMFS_SOURCE != ""
@ -196,6 +205,17 @@ config INITRAMFS_COMPRESSION_LZ4
If you choose this, keep in mind that most distros don't provide lz4
by default which could cause a build failure.
config INITRAMFS_COMPRESSION_ZSTD
bool "ZSTD"
depends on RD_ZSTD
help
ZSTD is a compression algorithm targeting intermediate compression
with fast decompression speed. It will compress better than GZIP and
decompress around the same speed as LZO, but slower than LZ4.
If you choose this, keep in mind that you may need to install the zstd
tool to be able to compress the initram.
config INITRAMFS_COMPRESSION_NONE
bool "None"
help


+ 1
- 0
usr/Makefile View File

@ -15,6 +15,7 @@ compress-$(CONFIG_INITRAMFS_COMPRESSION_LZMA) := lzma
compress-$(CONFIG_INITRAMFS_COMPRESSION_XZ) := xzmisc
compress-$(CONFIG_INITRAMFS_COMPRESSION_LZO) := lzo
compress-$(CONFIG_INITRAMFS_COMPRESSION_LZ4) := lz4
compress-$(CONFIG_INITRAMFS_COMPRESSION_ZSTD) := zstd
obj-$(CONFIG_BLK_DEV_INITRD) := initramfs_data.o


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