Trouble booting some RAM configs on V560TU

[filipleple]

Component

Dasharo firmware

Device

NovaCustom V56 14th Gen

Dasharo version

v0.9.0-rc6

Dasharo Tools Suite version

No response

Brief summary

Certain RAM configs will refuse to boot on V560TU - Intel Core Ultra 7 155H, or will boot only following a CMOS reset

How reproducible

70%

How to reproduce

Try to boot

• 2x16GB
• 32GB & 16GB
• 48GB & 32GB

Expected behavior

They should boot

Actual behavior

Most of the time, 2x16GB boots only after a CMOS reset, 32GB & 16GB won't boot no matter what and cause the power LED and keyboard backlight to flash. However, it's not 100% reproducible.

Screenshots

No response

Additional context

No response

Solutions you've tried

No response

[mkopec]

@filipleple Do you recall the CPU model of the affected laptop? Both combinations seem to work fine on V540TU w/ 155H on my end

[filipleple]

updated the issue to include the cpu model

[mkopec]

I believe there is an issue with MRC cache invalidation. On some RAM swaps, instead of invalidating cached MRC settings and re-training, FSP attempts to restore FSP settings which and fails. As a workaround, one can remove one memory module and boot with just the other one installed.

[mkopec]

soo, apparently the 16GB and 32GB modules produce the exact same SPD CRC, so FSP considers them the same and doesn't invalidate MRC cache. It seems like the RAM manufacturer is at fault here for not assigning an unique serial number to each module

[mkopec]

Workaround: Dasharo/coreboot@d7eb079

Confirmed to resolve the retraining issue. Users are expected to clear the CMOS when swapping memory modules