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0b2c29fb68
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>
58 lines
2.2 KiB
Makefile
58 lines
2.2 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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# to be include'd by arch/$(ARCH)/boot/Makefile after setting
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# EFI_ZBOOT_PAYLOAD, EFI_ZBOOT_BFD_TARGET, EFI_ZBOOT_MACH_TYPE and
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# EFI_ZBOOT_FORWARD_CFI
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quiet_cmd_copy_and_pad = PAD $@
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cmd_copy_and_pad = cp $< $@; \
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truncate -s $$(hexdump -s16 -n4 -e '"%u"' $<) $@
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# Pad the file to the size of the uncompressed image in memory, including BSS
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$(obj)/vmlinux.bin: $(obj)/$(EFI_ZBOOT_PAYLOAD) FORCE
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$(call if_changed,copy_and_pad)
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# in GZIP, the appended le32 carrying the uncompressed size is part of the
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# format, but in other cases, we just append it at the end for convenience,
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# causing the original tools to complain when checking image integrity.
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comp-type-y := gzip
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zboot-method-y := gzip
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zboot-size-len-y := 0
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comp-type-$(CONFIG_KERNEL_ZSTD) := zstd
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zboot-method-$(CONFIG_KERNEL_ZSTD) := zstd22_with_size
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zboot-size-len-$(CONFIG_KERNEL_ZSTD) := 4
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$(obj)/vmlinuz: $(obj)/vmlinux.bin FORCE
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$(call if_changed,$(zboot-method-y))
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# avoid eager evaluation to prevent references to non-existent build artifacts
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OBJCOPYFLAGS_vmlinuz.o = -I binary -O $(EFI_ZBOOT_BFD_TARGET) $(EFI_ZBOOT_OBJCOPY_FLAGS) \
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--rename-section .data=.gzdata,load,alloc,readonly,contents
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$(obj)/vmlinuz.o: $(obj)/vmlinuz FORCE
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$(call if_changed,objcopy)
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aflags-zboot-header-$(EFI_ZBOOT_FORWARD_CFI) := \
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-DPE_DLL_CHAR_EX=IMAGE_DLLCHARACTERISTICS_EX_FORWARD_CFI_COMPAT
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AFLAGS_zboot-header.o += -DMACHINE_TYPE=IMAGE_FILE_MACHINE_$(EFI_ZBOOT_MACH_TYPE) \
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-DZBOOT_EFI_PATH="\"$(realpath $(obj)/vmlinuz.efi.elf)\"" \
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-DZBOOT_SIZE_LEN=$(zboot-size-len-y) \
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-DCOMP_TYPE="\"$(comp-type-y)\"" \
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$(aflags-zboot-header-y)
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$(obj)/zboot-header.o: $(srctree)/drivers/firmware/efi/libstub/zboot-header.S FORCE
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$(call if_changed_rule,as_o_S)
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ZBOOT_DEPS := $(obj)/zboot-header.o $(objtree)/drivers/firmware/efi/libstub/lib.a
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LDFLAGS_vmlinuz.efi.elf := -T $(srctree)/drivers/firmware/efi/libstub/zboot.lds
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$(obj)/vmlinuz.efi.elf: $(obj)/vmlinuz.o $(ZBOOT_DEPS) FORCE
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$(call if_changed,ld)
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OBJCOPYFLAGS_vmlinuz.efi := -O binary
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$(obj)/vmlinuz.efi: $(obj)/vmlinuz.efi.elf FORCE
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$(call if_changed,objcopy)
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targets += zboot-header.o vmlinux.bin vmlinuz vmlinuz.o vmlinuz.efi.elf vmlinuz.efi
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