Currently the MRC cache is updated in romstage, immediately after
returning from FSP-M. Since cbmem is not cached in romstage, the update
is slow (~6 ms on nissa). Specifically, the new MRC data returned by the
FSP is stored in the FSP reserved memory in cbmem, so hashing the new
data is slow.
Move the MRC cache update to ramstage, where cbmem is cached. On nissa,
this saves ~5 ms of boot time.
Before:
552:finished loading ChromeOS VPD (RW) 631,667 (16)
3:after RAM initialization 637,703 (6,036)
4:end of romstage 650,307 (12,603)
After:
552:finished loading ChromeOS VPD (RW) 631,832 (15)
3:after RAM initialization 633,002 (1,169)
4:end of romstage 645,582 (12,580)
In ramstage, save_mrc_data() takes ~138 us.
BUG=b:242667207
TEST=MRC caching still works as expected on nivviks - after clearing the
MRC cache, memory is retrained on the next boot, but cached data is used
on subsequent boots.
Change-Id: Ie6aa2dee83a3ab8913830746593935d36a034b8d
Signed-off-by: Reka Norman <rekanorman@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/67669
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
7b5a93153a