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  1. #1
    New ROGer Array
    Join Date
    Jun 2019

    [SOLVED] AMD Vega 56/64 Passthrough on Threadripper X399 Motherboards


    I have recently been trying to do AMD VEGA GPU passthrough with a Linux Host and KVM/Virt-Manager/QEMU.
    The VM was always crashing.
    I narrowed down the problem to the passthrough of the GPU. If I passed through other devices, it was fine.

    I have finally managed to solve it.
    I appears that QEMU does not yet support PCI BAR resizing. The amdgpu driver in the guest tries to resize the bar from 256M to 8G and then tries to use it and you get a protection fault/crash.

    There is now a work around that works, that has reached qemu git master. Eventually it will be in qemu releases.
    So, no crashes any more.
    Tested with Linux kernel 5.1.11 on the host.

    The QEMU change that fixes the problem is:
    Description: vfio/pci: Hide Resizable BAR capability

    What this does is hide the resizable capability of the BAR, so amdgpu driver does not try to re-size it.
    Also tested with a Windows guest.
    3D Games in the guest work fine and are very fast.

    The system is very stable.

  2. #2
    ROG Member Array zasyadko PC Specs
    zasyadko PC Specs
    ProcessorAMD THREADRIPPER 1950X
    Memory (part number)Corsair Vengeance LPX (CMK64GX4M4A2400C14) 4x16GB Kit
    Graphics Card #1MSI Radeon RX Vega 64 WAVE 8G
    Graphics Card #2MSI Radeon RX Vega 64 WAVE 8G
    Graphics Card #3MSI Radeon RX Vega 64 WAVE 8G
    Graphics Card #4MSI Radeon RX Vega 64 WAVE 8G
    MonitorSamsung 55" UHD
    CaseThermaltake Core P7
    Power SupplyEnermax Platimax 1700W
    Headset SONY MDR-XB950N1
    OS Windows 10, Ubuntu 16.04

    Join Date
    Dec 2017

    Hello! Please tell me which distribution do you use? I just can’t get to work, I have Asus zenith extreme and 4 vega 64. Please share your tutorial on setting up virtual machines, thanks.

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