GT 750M Dumping Bios Takes ~2 Hours, eventually says EEPROM not supported

[xor7xorrrr]

Hi everyone, I'm attempting to dump the bios of the GT 750M in my MacBook pro from windows 8.1.

When I try to save the bios, gpu-z hangs and nvflash runs in the background forever at 20% cpu usage.
I've uninstalled the GeForce drivers, but no change. Similarly when I try to just run nvflash --save vbios.rom it hangs at 20% cpu. I've left it running for ~2 hours with no change.

I need the bios to get VGA passthrough to work from Linux, so if anyone has any ideas that would be a great help. I'm using GPU-Z 0.8.1

 

[W1zzard]

Did you disable your graphics adapter? (device manager, right click, disable)

Are you using the latest nvflash from our downloads section? Maybe try going through older versions.

 

[xor7xorrrr]

If I disable my graphics adapter how will I be able to dump the bios? Would I need to ssh into this machine or something? I was using the latest version, although I observed the same behavior with the previous version as well.

 

[W1zzard]

It will switch to standard VGA. Not sure if that's gonna work on your notebook, fine on desktop, worth a try.

 

[xor7xorrrr]

Ok, my display still works, but the behavior didn't change. It's worth noting that any command, nvflash --list, --check etc hangs the same way

 

[xor7xorrrr]

Just tested with older versions, nvflash 5.95.0.1 didn't detect any adapters, nvflash 5.134 and 5.142 found the card but said no supported EEPROM found, and nvflash 5.164 hangs in the same way as the the newer versions.

EDIT: Left the latest version running and after ~3 hours it ultimately returns no supported EEPROM found so it would seem that no versions of nvflash works for me.

 

[rb3]

@xor7xorrrr Hi, have you had any progress with passing through the GT 750m? I was able to get the ROM dump for my mid-2014 rMBP (same card) from Linux by using the mapped memory technique documented at http://coreboot.org/VGA_support#UEFI_Method. However, using the ROM parser documented at http://vfio.blogspot.com/2014/08/does-my-graphics-card-rom-support-efi.html, it doesn't seem like the GPU ROM supports EFI, which is needed for OVMF to work (documented at https://bbs.archlinux.org/viewtopic.php?id=162768).

Does anyone have an idea on how to write an EFI-compatible ROM for my graphics card?