[vfio-users] BIOS memory mapping or chipset issue with MMIO prevents IGD pass-through in legacy mode?

[Alex Williamson]

On Wed, 27 Jul 2016 17:30:37 -0700
globalgorrilla at fastmail.fm wrote:
> > > qemu.log:
> > > qemu-system-x86_64: -device
> > > vfio-pci,host=00:02.0,id=hostdev0,bus=pci.0,addr=0x2: IGD device
> > > 0000:00:02.0 failed to enable VGA access, legacy mode disabled  
> > 
> > Is you kernel built with CONFIG_VFIO_PCI_VGA=y?  
> 
> Yes.
> 
> % zcat /proc/config.gz | grep CONFIG_VFIO_PCI_VGA
> CONFIG_VFIO_PCI_VGA=y

Hmm, the kernel not exposing the VGA regions is really the only way we
can fail here and the only two ways that the kernel won't expose VGA,
given that enabled in the config, is if the device isn't VGA (which we
can see by your class code, it is) or if the disable_vga option to
vfio_pci is used.  You don't happen to have that left over from
assigning discrete devices, do you?

# cat /sys/module/vfio_pci/parameters/disable_vga