Hello,
A system with ICX server processors (Dx/M1 steppings) cannot fully boot into the EFI shell when using a UEFI firmware image with updated microcode. Through experimentation, it was found that a #GP exception occurs when trying to write in SMM mode an undocumented MSR 0x790 with a value of '0'. This behavior is characteristic of microcode versions: 0x0d0003a5, 0x0d0003b9, 0x0d0003d1, 0x0d0003e7. When using a UEFI firmware image with microcode version 0x0d000390, the system successfully boots into the EFI shell. The release notes for SFUP R01.01.0009 mention a similar issue: [IPU2023.3][HSD]:[14018718770] BIOS writes 0x790 before BIOS_DONE caused GPF when DAM is not enabled. However, the point is that the Delayed Authentication Mode is enabled in the UEFI firmware image, as verified using the spsFITc utility.
How can this behavior be fixed?
