Second GPU passthrough - no "bios" post

[quei]

Hi All

i am really new with proxmox so i am testing actually the possibilities.
Shortly to my setup and what i plan to do:

VM 1
Windows 11 with 2080 TI passthrough (already setup and working fine)

VM 2
MacOS 12 with RX 580 passthrough (vm set up and working)

Used Hardware:
Asus B550 Gaming (wi-fi)
64 GB RAM
nvidia 2080 TI
Radeon rx 580

So, i know that MacOS is not supported here but my problem has nothing to do with MacOS in general.
The strange thing here is that when i boot the second VM (OS independent) the GPU will not show me the "BIOS" POST.
Both VMs are configured with OVMF (UEFI), on the Windows VM i can see the POST with the proxmox logo.
If i check the rx 580 with GPUZ i see that UEFI is enabled, even if i attach the GPU to the Windows VM i didnt see the POST.
I also tried to map the rom in the conf of the VM but this also didnt solve the issue...

Is this a known issue, what can i check or test in this case?
I have also played around with the CSM settings of the BIOS and that seems also not to fix my issue...

Maybe some usefull side info, i see the real BIOS POST of the Hardware only on the first (nvidia gpu) Monitor.
Any hints or helping links for this issue?

 

[leesteken]

Is the problem that it does not show the virtual BIOS POST screen but works fine later when the desktop environment of the VM is running? Or does the VM not start and hangs with a black screen or the GPU is not recognized/usable by the VM? The latter case might be because the RX 580 does not (always) reset properly and vendor-reset will probably help.

EDIT: AMD GPUs work better with Primary GPU disabled (with display set to none), while NVidia ones work better with it enabled, in my experience.

 

[quei]

well in the end the problem is that the GPU is not showing any signal and the OS (Windows or MacOS) crashes

if i attach the AMD GPU to Windows then windows makes bluescreen...
anytime if windows try to initialize the GPU it creates bluescreen.
i also read about the "vendor-reset" bug, but then i should see some errors with dmesg but this is not the case here...
the GPU seems to be dead... BUT if i run windows native the GPU gets initialized after BIOS POST.

well... actually i didnt have any clue what the problem can be...
what i know is the GPU is not dead, in native mode it works after BIOS POST.

i think i will flash the GPU with a rom that i found online...
maybe it really the GPU which didnt work well... but the native case really confuses me a lot...

can it be a "wrong" setting in the BIOS?