For radeon, you can look in /sys. eg. we see /sys/devices/pci0000:00/0000:00:0b.0/0000:04:00.0/rom, and first we `echo 1 > rom` to prevent "invalid argument" error, and then `cat rom > ~/yourfile.rom` and you have it.
For nouveau, you have to bind nouveau driver (rather than vfio-pci) and you can find it somewhere like /sys/kernel/debug/dri/0/vbios.rom
FYI I had a similar issue years ago until I figured out that adding the vgarom file fixes it, eg.:
-device vfio-pci, host=04: 00.0,bus= root.1, multifunction= on,x-vga= on,addr= 0.0,romfile= Sapphire. R7260X. 1024.131106. rom
For radeon, you can look in /sys. eg. we see /sys/devices/ pci0000: 00/0000: 00:0b.0/ 0000:04: 00.0/rom, and first we `echo 1 > rom` to prevent "invalid argument" error, and then `cat rom > ~/yourfile.rom` and you have it.
For nouveau, you have to bind nouveau driver (rather than vfio-pci) and you can find it somewhere like /sys/kernel/ debug/dri/ 0/vbios. rom