[vfio-users] when is ROM extraction needed and how to do it correctly?

[Daniel Pocock]

In which cases are these ROMs actually needed? For example, is the ROM
needed if the passthrough video device is secondary display? Is the ROM
needed if using UEFI / OVMF instead of SeaBIOS?

I've extracted ROMs from each GPU using the method:

  find /sys/devices -name rom

to discover the devices with a ROM.  For the device I want to use, I've
used something like the following to extract the ROM (based on the paths
found by the find command):


ROM=/sys/devices/pci0000\:40/0000\:40\:03.0/0000\:42\:00.0/rom

echo 1 | tee "${ROM}"
cat "${ROM}" > my-vga-device.rom

I've also read that some devices modify a copy of their ROM data during
boot.  Does the method described above access the original ROM content
or the modified content?  If it is accessing modified content, is there
a way to get the original ROM content, either generically or in a method
specific to each vendor?