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authorSubrata Banik <subratabanik@google.com>2024-02-15 23:49:36 +0530
committerSubrata Banik <subratabanik@google.com>2024-02-18 03:13:45 +0000
commite29c3e748d83dba01722961cd9947704be05ff6e (patch)
tree43975e739b0f2366c8ae4bf7a4b0178ea488780f /src/soc/sifive
parentc9c88fb598fb450c5171c823a72517087af8fe17 (diff)
soc/intel/mtl: Skip RW CBFS ucode update if RO is locked
This patch eliminates coreboot from loading microcode from RW CBFS (when the RO descriptor is locked, which indicates a fixed RO image) because the kernel can already patch the microcode on BSPs and APs while booting to OS. This may be a chance to lower the burden on the AP FW side because patching microcode on in-field devices is subject to firmware updates, which are rarely published and, if required, must go through the firmware qualification testing procedure (which is costly, unlike kernel updates for ucode updates). 1. The FIT loads the necessary microcode from the RO during reset. 2. Reloading microcode from RW CBFS impacts boot time (~60ms, core-dependent). 3. The kernel can still load microcode updates. ChromeOS devices leverage RO+RW-A/RW-B booting. The RO's microcode is sufficient for initial boot, and the kernel can apply updates later. BUG=none TEST=Verified boot optimization; in-field devices skip RW-CBFS microcode loading when RO is locked. Change-Id: Ia859809970406fca3fa14e6fa8e766ab16d94c8a Signed-off-by: Subrata Banik <subratabanik@google.com> Reviewed-on: https://review.coreboot.org/c/coreboot/+/80567 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: YH Lin <yueherngl@google.com>
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