[XS] Change in coreboot[master]: mb/google/rex: change ramstage compression to LZ4

[Wonkyu Kim (Code Review)]

Attention is currently required from: Kapil Porwal, Subrata Banik, Tarun Tuli.

Hello Kapil Porwal, Subrata Banik, Tarun Tuli,

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/coreboot/+/75769?usp=email

to look at the new patch set (#2).

Change subject: mb/google/rex: change ramstage compression to LZ4
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mb/google/rex: change ramstage compression to LZ4

for saving boot time, change ramstage compression from LZMA to LZ4.
Boot time saving is around 35ms(30-37ms) while SPI size impact is 230KB.
For detail, refer below.

Exising: LZMA(55.6 ms)
   8:starting to load ramstage                         894,519 (0)
  15:starting LZMA decompress (ignore for x86)         903,556 (9,036)
  16:finished LZMA decompress (ignore for x86)         949,997 (46,441)
   9:finished loading ramstage                         950,179 (182)

Changed: LZ4(17.8ms)
   8:starting to load ramstage                         900,876 (0)
  17:starting LZ4 decompress (ignore for x86)          917,650 (16,774)
  18:finished LZ4 decompress (ignore for x86)          918,690 (1,040)
   9:finished loading ramstage                         918,849 (158)

Size impact( 73KB * 3 = 219KB)
fallback/ramstage              0x62940    stage          240281 LZ4  (405524 decompressed)
fallback/ramstage              0x62940    stage          165452 LZMA (405524 decompressed)

BUG=b:286930648
TEST= Boot to OS and check boot time

Signed-off-by: Wonkyu Kim 
Change-Id: I6610f405d287bff2eb4eee6f09026e3361405ded
---
M src/mainboard/google/rex/Kconfig
1 file changed, 1 insertion(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/69/75769/2