This adds the option to compress ramstage and payloads with zstd.
zstd compressed ramstages are typically +5% bigger than lzma compressed
ramstages. The decompressor .text section grows by 20KiB and the
decompressor needs 16KiB more heap than the lzma decompressor.
To use less heap inside the zstd decompressor the build time define
ZSTD_DECODER_INTERNAL_BUFFER is used.
Quote:
The build macro `ZSTD_DECODER_INTERNAL_BUFFER` can be set to control
the amount of extra memory used during decompression to store
literals. This defaults to 64kB. Reducing this value reduces the
memory footprint of `ZSTD_DCtx` decompression contexts, but might
also result in a small decompression speed cost
TEST=Booted on Lenovo X220 with zstd ramstage showed no disadvantage
over a bigger internal buffer used.
TEST=Booted on Lenovo X220. The zstd decompressor is twice as fast
as the lzma decompressor.
cbmem -t shows:
- finished ZSTD decompress (ignore for x86) 79,444 (24,494)
- finished LZMA decompress (ignore for x86) 94,971 (45,545)
TEST=Booted on QEMU Q35, QEMU aarch64 virt, QEMU riscv RV64 with
zstd compressed ramstage.
Change-Id: Ic1b1f53327c598d07bd83d4391e8012d41696a16
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/69893
Reviewed-by: Julius Werner <jwerner@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
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