[vfio-users] VGA Passthrough fails without NoSnoop patch

[Nick Sarnie]

Have you tried a BIOS install and setting x-vga=on? With my 480, there is
no UEFI image or it got corrupted somehow, so I need to pass a UEFI vbios I
downloaded to see the screen if I use UEFI. With BIOS, x-vga=on works.



On Sun, Jan 29, 2017 at 2:55 PM, Javier Celaya <jcelaya at gmail.com> wrote:

> Hello list
>
> I've been looking for it, but I cannot find a solution to this problem. I
> have a working Windows 10 VM with UEFI boot, which I pass an AMD Radeon RX
> 480. It also worked with a NVIDIA GTX 550Ti I had before. The thing is, it
> only works with a QEMU 2.2 patched with the NoSnoop fix. With any later
> release of QEMU, or without the patch, the VM:
> - Throws an Error 43 with the NVIDIA card.
> - Goes black on boot and reboots some seconds later with the AMD card
> The vfio FAQ says that patch is not needed with a later release of QEMU,
> so I'm wondering what I'm doing wrong...
>
> My hardware is an Intel i5 2500, ASUS motherboard with a Z68 chipset, 16GB
> of RAM. Both graphics cards appear in their own iommu group with the HDMI
> sound card.
>
> My QEMU command line is:
>
> src/qemu/build-2.2-NoSnoop/x86_64-softmmu/qemu-system-
> x86_64
>
>         -nodefaults -no-user-config
>
>
>         -enable-kvm -m 8192
>
>
>         -cpu Opteron_G1,+cx16,+lahf_lm,kvm=off
>
>
>         -M q35
>
>
>         -smp 4,sockets=1,cores=4,threads=1
>         -realtime mlock=on -rtc base=localtime,driftfix=slew
>         -drive file="OVMF_CODE-pure-efi.fd",if=pflash,format=raw,unit=0,
> readonly=on
>         -drive file="OVMF_VARS-pure-efi.fd",if=pflash,format=raw,unit=1
>         -drive file="$HD",id=disk1,if=virtio,cache=none
>         -netdev bridge,id=netuser,br=br0
>         -device virtio-net-pci,netdev=netuser,
> id=net0,mac=52:54:00:72:75:9e
>         -device ich9-intel-hda,id=sound0
>         -device hda-duplex,id=sound0-codec0,bus=sound0.0,cad=0
>         -device ioh3420,bus=pcie.0,multifunction=on,port=1,
> chassis=1,id=root.0
>         -usbdevice $JOYPAD
>         -usbdevice $KEYBOARD
>         -usbdevice $MOUSE
>         -mem-path $MEM_PATH
>
>         -nographic -vga none
>         -device vfio-pci,host=01:00.0,id=hostdev0,bus=root.0,
> multifunction=on,x-vga=on
>         -device vfio-pci,host=01:00.1,id=hostdev1,bus=pcie.0
>
> I have tried, with the same results:
> - Using the pc-i440fx machine
> - Connecting the HDMI sound card to another bus
> - Not connecting the HDMI sound card at all
> - Using -cpu host (Windows 10 hangs with this configuration)
> - Using -cpu core2duo
>
> Any other idea?
> Thank you
>
> Javi
>
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>
>
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