diff options
| author | Ard Biesheuvel <ardb@kernel.org> | 2024-12-06 11:41:40 +0100 |
|---|---|---|
| committer | Ard Biesheuvel <ardb@kernel.org> | 2024-12-06 16:59:56 +0100 |
| commit | 0b2c29fb68f8bf3e87a9d88404aa6fdd486223e5 (patch) | |
| tree | f599c2b113be2d37f7b16c647042c3e7e4abd553 /drivers/firmware | |
| parent | 40384c840ea1944d7c5a392e8975ed088ecf0b37 (diff) | |
efi/zboot: Limit compression options to GZIP and ZSTD
For historical reasons, the legacy decompressor code on various
architectures supports 7 different compression types for the compressed
kernel image.
EFI zboot is not a compression library museum, and so the options can be
limited to what is likely to be useful in practice:
- GZIP is tried and tested, and is still one of the fastest at
decompression time, although the compression ratio is not very high;
moreover, Fedora is already shipping EFI zboot kernels for arm64 that
use GZIP, and QEMU implements direct support for it when booting a
kernel without firmware loaded;
- ZSTD has a very high compression ratio (although not the highest), and
is almost as fast as GZIP at decompression time.
Reducing the number of options makes it less of a hassle for other
consumers of the EFI zboot format (such as QEMU today, and kexec in the
future) to support it transparently without having to carry 7 different
decompression libraries.
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Diffstat (limited to 'drivers/firmware')
| -rw-r--r-- | drivers/firmware/efi/Kconfig | 4 | ||||
| -rw-r--r-- | drivers/firmware/efi/libstub/Makefile.zboot | 18 |
2 files changed, 6 insertions, 16 deletions
diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig index e312d731f4a3..5fe61b9ab5f9 100644 --- a/drivers/firmware/efi/Kconfig +++ b/drivers/firmware/efi/Kconfig @@ -76,10 +76,6 @@ config EFI_ZBOOT bool "Enable the generic EFI decompressor" depends on EFI_GENERIC_STUB && !ARM select HAVE_KERNEL_GZIP - select HAVE_KERNEL_LZ4 - select HAVE_KERNEL_LZMA - select HAVE_KERNEL_LZO - select HAVE_KERNEL_XZ select HAVE_KERNEL_ZSTD help Create the bootable image as an EFI application that carries the diff --git a/drivers/firmware/efi/libstub/Makefile.zboot b/drivers/firmware/efi/libstub/Makefile.zboot index 65ffd0b760b2..48842b5c106b 100644 --- a/drivers/firmware/efi/libstub/Makefile.zboot +++ b/drivers/firmware/efi/libstub/Makefile.zboot @@ -12,22 +12,16 @@ quiet_cmd_copy_and_pad = PAD $@ $(obj)/vmlinux.bin: $(obj)/$(EFI_ZBOOT_PAYLOAD) FORCE $(call if_changed,copy_and_pad) -comp-type-$(CONFIG_KERNEL_GZIP) := gzip -comp-type-$(CONFIG_KERNEL_LZ4) := lz4 -comp-type-$(CONFIG_KERNEL_LZMA) := lzma -comp-type-$(CONFIG_KERNEL_LZO) := lzo -comp-type-$(CONFIG_KERNEL_XZ) := xzkern -comp-type-$(CONFIG_KERNEL_ZSTD) := zstd22 - # in GZIP, the appended le32 carrying the uncompressed size is part of the # format, but in other cases, we just append it at the end for convenience, # causing the original tools to complain when checking image integrity. -# So disregard it when calculating the payload size in the zimage header. -zboot-method-y := $(comp-type-y)_with_size -zboot-size-len-y := 4 +comp-type-y := gzip +zboot-method-y := gzip +zboot-size-len-y := 0 -zboot-method-$(CONFIG_KERNEL_GZIP) := gzip -zboot-size-len-$(CONFIG_KERNEL_GZIP) := 0 +comp-type-$(CONFIG_KERNEL_ZSTD) := zstd +zboot-method-$(CONFIG_KERNEL_ZSTD) := zstd22_with_size +zboot-size-len-$(CONFIG_KERNEL_ZSTD) := 4 $(obj)/vmlinuz: $(obj)/vmlinux.bin FORCE $(call if_changed,$(zboot-method-y)) |