From: Nick Terrell <terrelln@xxxxxx> * 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. Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> Tested-by: Sedat Dilek <sedat.dilek@xxxxxxxxx> Signed-off-by: Nick Terrell <terrelln@xxxxxx> --- usr/Kconfig | 20 ++++++++++++++++++++ usr/Makefile | 1 + 2 files changed, 21 insertions(+) diff --git a/usr/Kconfig b/usr/Kconfig index 96afb03b65f9..2599bc21c1b2 100644 --- a/usr/Kconfig +++ b/usr/Kconfig @@ -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 diff --git a/usr/Makefile b/usr/Makefile index c12e6b15ce72..b1a81a40eab1 100644 --- a/usr/Makefile +++ b/usr/Makefile @@ -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 -- 2.27.0
