[vfio-users] BAR 0: can't reserve

[Zycorax Tokoroa]

have you tried using a different slot for the passtrough'ed card? With 
the exception of some Gigabyte motherboards that allow switching the 
primary graphics device the first slot is usually reserved/hooked during 
the boot to display GRUB stuff and early pre-vfio loading kernel stuff. 
I think efifb might claim the device in that moment. I recall reading of 
someone having built the kernel with efifb as a module, and thus could 
unload it later on

> vfio-pci 0000:01:00.0: BAR 0: can't reserve [mem 0xc0000000-0xcfffffff
> 64bit pref]
>
> cat /proc/iomem shows...
> b0000000-ffffffff : PCI Bus 0000:00
>    b0000000-bfffffff : PCI Bus 0000:02
>      b0000000-bfffffff : 0000:02:00.0
>    c0000000-cfffffff : PCI Bus 0000:01
>      c0000000-cfffffff : 0000:01:00.0
>        c0000000-c02fffff : efifb
>
>> efifb
>
> How do i get rid of it?
> Seems like it's blocking my videocard.
> GRUB2 options aren't showing anything of value.
> Host system has proprietary nvidia driver installed, linux cmdline is:
> BOOT_IMAGE=/vmlinuz-4.4.7-300.fc23.x86_64
> root=UUID=c58981f4-3223-4b94-ba68-24dc9a553750 ro nomodeset rhgb quiet
> amd_iommu=on iommu=pt LANG=en_US.UTF-8
>
> Also, that seems to be the reason for my libvirtd hanging up on guest
> kill, since i've got a funny kernel oops in dmesg:
> https://paste.fedoraproject.org/360833/18732521/
>
>
> Halp.
>
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