Bar 0: can't reserve mem

Software & Operating Systems VFIO
1

Hey guys, I hope you can help me get over that Bar 0 error! My server is a GA-AB350N-GAMING WFI with a R1600 and an 7870 running headless (so it’s obviously my boot graphics…)!

For some reason my GPU shows a black screen when trying to pass it to a VM! My Radeon is modded to support UEFI by the way. The dmesg output below appears when trying to boot the VM:

[  191.626734] vfio_ecap_init: 0000:09:00.0 hiding ecap 0x19@0x270
[  191.626742] vfio_ecap_init: 0000:09:00.0 hiding ecap 0x1b@0x2d0
[  191.627512] vfio-pci 0000:09:00.0: BAR 0: can't reserve [mem 0xe0000000-0xefffffff 64bit pref]
[  192.800847] device enp8s0 entered promiscuous mode
[  201.465708] device enp8s0 left promiscuous mode

My boot args are:

amd_iommu=on iommu=pt iommu=1 rd.driver.pre=vfio-pci module_blacklist=amdgpu,radeon vfio_iommu_type1.allow_unsafe_interrupts=1 video=vesafb:off,efifb:off

I’m actually not entirely sure which of them I actually really need (except vfio_iommu_type1.allow_unsafe_interrupts=1 ), but I suppose it doesn’t really matter…

Does it make a difference that I put my device ids in the modprobe.d folder as opposed to an initramfs script?

Thanks in advance!

2

Weirdly enough when booting a live image of Alpine for eg, lsmod shows the Radeon mod being loaded… What the heck …

3

Does anybody have an idea? :frowning:

4

This happens when booting the vm with Bar disabled and Bar 0 enabled and supplied vbios! Though when I don’t supply a bios it will also give me an error saying “vfio-pci 0000:09:00.0: No more image in the PCI ROM” What the heck? What is Bar 0 even??

5

And yes it’s an EFI vBIOS, I even patched it myself and the system is able to post the system with csm disabled! Beforehand it always defaulted back to enabled !

6

Nice,
I did fix it now with the help of reddit!

It so happened to be the flag video=vesafb:off,efifb:off! It doesn’t work for some reason, so I changed it to video=efifb:off just to test it and that did the trick!

Soooooooo glad that it works now!!!