From: Ard Biesheuvel <ardb@xxxxxxxxxx> 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. Cc: Gerd Hoffmann <kraxel@xxxxxxxxxx> Cc: Peter Jones <pjones@xxxxxxxxxx> Cc: Pingfan Liu <piliu@xxxxxxxxxx> Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx> --- drivers/firmware/efi/Kconfig | 4 ---- 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)) -- 2.47.0.338.g60cca15819-goog
