Weird bug of NvmExpressDxe_2.ffs on Clevo P655SA

BIOS/UEFI Modding Reports: BIOS Modding Results
1

I have offered my modified BIOS to some P655SA users who want to use NVME SSDs.
According to their feedback, the NVME SSD bootstrap in UEFI mode is OK, but while in legacy mode (in order to boot into DOS from USB flash drive or something else that doesn’t support UEFI) with NVME SSD present, after POST screen, it gives only black screen with a blinking underscore. This bug happens only when both NVME SSD and NvmExpress_2.ffs are present.

I managed to solve this by using NVME modules from Asrock Z87 mo-bo’s BIOS instead. @Fernando

2

@Ferrous :
Thanks for your report, which really surprises me, because the EFI BIOS modules are only loaded while booting in UEFI mode. So while booting in LEGACY mode the code of the inserted NVNMe DXE module should not matter.

Did you insert just the NVMe.ffs module or all 3 ASRock BIOS modules with the word “NVMe“ in it?

3

All 3 NVME modules: Nvme.ffs, NvmeSmm.ffs and NvmeINT13.ffs .
EDIT: I think the NvmeINT13.ffs does something about BIOS Interrupt 13h, which controls disk I/O.

4

Thanks for the clarification.
So it seems possible, that the issue hasn’t been caused by the inserted NvmExpressDxE_2.ffs itself, but by the missing second or third NVMe related BIOS module.
Thie relationship between these 3 modules has to be investigated.

5

I think the NvmeINT13.ffs does something about BIOS Interrupt 13h, which controls disk I/O. There are also some modules named xxxINT13 such as USBINT13, AINT13(AHCI) present.