cat: rom: Input/output error

[mgsqz]

Hi,It's seems didn't work on proxmox 5.4-11
platform：
cpu:i7-3820qm
chipset:hm77
GPU:NVIDIA Corporation GF108M [GeForce GT 635M]

root@nserver:~# cd /sys/bus/pci/devices/0000:01:00.0/
root@nserver:/sys/bus/pci/devices/0000:01:00.0# echo 1 > rom
root@nserver:/sys/bus/pci/devices/0000:01:00.0# cat rom > /tmp/image.rom
cat: rom: Input/output error

dmesg:
vfio-pci 0000:01:00.0: Invalid PCI ROM header signature: expecting 0xaa55, got 0xffff

what's wrong?

[nordmagnus999]

I have run into the same problem (as i have a optimus laptop too by looking at your spec).

Basically, some dgpu in optimus laptop don't have the rom loaded from the gpu directly (afaik most desktop gpu do the reverse here) or just don't have enough permissions to do it, or even because the gpu is still in use (aka most optimus gpu don't support hotswapping); afaik that's all the reason i can think of but i could be wrong.
But fortunately, there is still ways to get the rom of the gpu:

• On windows, the rom is loaded as a .reg file in the registry, so you can get it there (more info here)
• You can use either vbiosfinder or romparser on the update/dump of your bios (romparser is already included in vbiosfinder btw).which you can usually find on the manufacturer site or if normal dumping tools support your bios already...
• If the above doesn't work (which would surprise me, but just in case), you can use binwalk on each file from the bios dump until you see something akin to "manufacturer's name" or "gpu vendor" or anything similar.

[ruthan]

I have some problem with some older cards, especially ATI ones.. On normal desktop PC.

[abigchopstick]

you can only get the rom file in BIOS boot mode it seems, try boot your system in legacy mode with a linux distro and do that again.

[sjkhsl]

root@pve:/# cd /sys/bus/pci/devices/0000:02:00.0/
root@pve:/sys/bus/pci/devices/0000:02:00.0# echo 1 > rom
root@pve:/sys/bus/pci/devices/0000:02:00.0# cat rom > /tmp/image.rom
cat: rom: Input/output error
root@pve:/sys/bus/pci/devices/0000:02:00.0# echo 0 > rom

My PVE system shows this. What should I do?

[tophrr]

@sjkhsl,
As abigchopstick said, try booting in Legacy mode from USB using another distro.
I used Ubuntu Server and successfully dumped my ROM the usual way.

[KEV936]

I want to dump the rocketlake rom, is it possible?

[zhaozhao]

Try to enable CSM in your host bios/uefi settings.
Works for me.

[ruthan]

Still it would be nice to print some error that CSM is not enable etc..

[startergo]

There is a workaround:

find /sys/devices -name rom
/sys/devices/pci0000:64/0000:64:00.0/0000:65:00.0/0000:66:08.0/0000:67:00.0/0000:68:00.0/0000:69:00.0/rom
/sys/devices/pci0000:64/0000:64:00.0/0000:65:00.0/0000:66:10.0/0000:6a:00.0/0000:6b:00.0/0000:6c:00.0/rom
/sys/devices/pci0000:16/0000:16:00.0/0000:17:00.0/0000:18:08.0/0000:19:00.0/0000:1a:10.0/0000:22:00.0/0000:23:00.0/0000:24:00.0/rom
/sys/devices/pci0000:16/0000:16:00.0/0000:17:00.0/0000:18:08.0/0000:19:00.0/0000:1a:04.0/0000:1b:00.0/rom

sudo su
setpci -s 0000:24:00.0 COMMAND=2:2 (manually manipulate the memory enable bit with setpci)
export PATH_TO_ROM=/sys/devices/pci0000:16/0000:16:00.0/0000:17:00.0/0000:18:08.0/0000:19:00.0/0000:1a:10.0/0000:22:00.0/0000:23:00.0/0000:24:00.0/rom
echo 1 > $PATH_TO_ROM
mkdir -p /var/lib/libvirt/vbios/
cat $PATH_TO_ROM > /var/lib/libvirt/vbios/gpu.rom
echo 0 > $PATH_TO_ROM
setpci -s 0000:24:00.0 COMMAND=0:2 (Clear memory enable bit with setpci)
exit

[ruthan]

Workaround without any comment how Linuxian.. its possible just to create some script etc for normal human beings?

[startergo]

Workaround without any comment how Linuxian.. its possible just to create some script etc for normal human beings?

Maybe I should just delete my previous comment to prevent normal human beings confusion? :)
I will gladly do so. Just let me know.

[yjun123]

@startergo Hi, I try your workaround, but it doesn't work for me. :(

root@pve:/sys/bus/pci/devices/0000:00:02.0# setpci -s 0000:00:02.0 COMMAND=2:2 
root@pve:/sys/bus/pci/devices/0000:00:02.0# echo 1 > rom
root@pve:/sys/bus/pci/devices/0000:00:02.0# cat rom  > /tmp/image.rom
cat: rom: Input/output error

[startergo]

but it doesn't work for me

You need to first find the rom location:

find /sys/devices -name rom

Then after enabling the memory enable bit with setpci :

echo 1 > "discovered_full_path_to_the_rom"

Just like in the example above.

[yjun123]

@startergo
I post the complete command log output below.

root@pve:~# find /sys/devices -name rom
/sys/devices/pci0000:00/0000:00:02.0/rom
root@pve:~# cd /sys/devices/pci0000:00/0000:00:02.0
root@pve:/sys/devices/pci0000:00/0000:00:02.0# setpci -s 0000:00:02.0 COMMAND=2:2 
root@pve:/sys/devices/pci0000:00/0000:00:02.0# echo 1 > rom 
root@pve:/sys/devices/pci0000:00/0000:00:02.0# cat rom  > /tmp/image.rom
cat: rom: Input/output error