On Sun, 10 Mar 2019 18:06:37 -0400 Nicolas Roy-Renaud <nicolas.roy-renau...@ens.etsmtl.ca> wrote:
> I've seen a lot of people before reccomand VFIO newcomers to flash their > GPU if they couldn't get their passthrough working right before, and > since I know how potentially risky and avoidable this sort of procedure > is (since QEMU lets you just pass your own ROM to the VM to be used > instead), and while attempting to go through the steps myself > <http://vfio.blogspot.com/2014/08/does-my-graphics-card-rom-support-efi.html> > (even though I've had a working VFIO setup for years), got something > unexpected. > > Attempting to dump the ROM from my guest card _/freshly /_/_after a > reboot_/ results in the following error message : > > cat: '/sys/bus/pci/devices/0000:07:00.0/rom': Input/output error > > Accompanied by the following like in dmesg : > > [ 1734.316429] vfio-pci 0000:07:00.0: Invalid PCI ROM header signature: > expecting 0xaa55, got 0xffff If lspci for the device reports: Control: I/O- Mem- BusMaster- ... (specifically Mem-), this could be the reason it's failing. The PCI ROM BAR is a memory region and memory decode needs to be enabled on the device in order to get access to it. Also if you have the device already bound to vfio-pci, the device might be in a D3 low power state, which could make that memory region unavailable. You can use the 'enable' file in sysfs to fix both of these, so your sequence would look like this: echo 1 > /sys/bus/pci/devices/0000:07:00.0/enable echo 1 > /sys/bus/pci/devices/0000:07:00.0/rom cat /sys/bus/pci/devices/0000:07:00.0/rom > gpu.rom echo 0 > /sys/bus/pci/devices/0000:07:00.0/rom echo 0 > /sys/bus/pci/devices/0000:07:00.0/enable Thanks, Alex _______________________________________________ vfio-users mailing list vfio-users@redhat.com https://www.redhat.com/mailman/listinfo/vfio-users
