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Re: [Xen-users] Fwd: GPU Passthrough


I have configured GPU Passthrough and in principle it works but I have some issues:

I can only start once the HVM DomU, if I shutdown it an want to start again then dom0 isnt responsible anymore - I need to hard reset the whole computer... What can be the problem?

I dont have a monitor/keyboard/mouse on the HVM domU and VNC doesnt work with the passed AMD GPU.

I've tried to passthrough the whole USB Controller but it doesnt work (errors at start the domU)
I've tried USB passthrough with:

usb = 1
usbdevice = [ "tablet", "host:3.4" ]

but this doesnt work to...

If I try to connect to the first gpu of the domU (not the AMD GPU) then I see only a black screen. It is possible to get the VNC working on the second AMD GPU?

Without this I cant set the resolution etc...

my config:

memory = 8192
vcpus = 8
pae = 1
acpi = 1
apic = 1
viridian = 1
rtc_timeoffset = 0
localtime = 1
on_poweroff = "destroy"
on_reboot = "restart"
on_crash = "restart"
sdl = 0
vnc = 1
vncunused = 0
vncdisplay = 100
vnclisten = ""
vif = [ "mac=00:16:3e:05:01:10,bridge=xenbr5,script=vif-bridge,model=e1000" ]
parallel = "none"
serial = "none"
type = "hvm"
boot = "d"
disk = [ "format=raw,vdev=hda,access=rw,backendtype=phy,target=/dev/vg_lilith/lv_marax_c", "format=raw,vdev=hdb,access=rw,backendtype=phy,target=/dev/vg_lilith/lv_marax_d" ]
max_grant_frames = "128"
gfx_passthru = 0
pci = [ "01:00.0", "01:00.1", "00:1b.0" ]
pci_permissive  = 1

Is there something else what I should change in the conig for better performance?

On Sat, Jun 30, 2018 at 5:40 AM, Christoph <mangel@xxxxxx> wrote:


I think about create a windows HVM domU with gpu passthrough on xen
to stream via steam games to my linux workstation.
I have some question about this setup:

1. Have someone tried it? Does it work as expected?
2. What is easier and what is most stable: primary or secondary gpu
passthrough? (I have a ATI Radeon HD 6950 GPU now but I want to buy
a nvidia in the near future)
3. Which settings gives the windows domU the needed priority? (I
have some PV linux domU's on this hypervisor, they should work
simultaneously but the most ressources should get the windows domU
becaues of play a game)
4. What would be the virtualization loss vs bare metal windows?

(1) I have a Windows HVM that I'm doing GPU passthrough, it's running
Windows 10 (originally Windows 8).  I use it to play games (mostly
from Steam).
I'm running on Xen 4.9, Dom0 is Debian 9.0 "Stretch".

Here are a few things to note:

* Obviously, your CPU needs to have an IOMMU. For Intels, that's VT-d
support.  I think that your Xeon will qualify (I have a Core i7,
specifically a i7-4790S)

* Less well known is this: Your motherboard, and particularly your
BIOS, need to have some mojo going on to make GPU passthrough work.  I
don't know why.
    ASRock motherboards seem to have good IOMMU support; my setup is
on an ASRock  H97M Pro4.

* Don't go with nVidia; their drivers are specifically designed to
*not* work with GPU passthrough unless you have a (very expensive)
Quattro card.

* ATI/AMD cards, on the other hand, don't support something called
FLR, which means (2) they're unsuitable for being passed in as the
primary GPU.
    My Windows DomU has the cirrus VGA passed-through as the primary
GPU; Windows is configured to ignore that GPU and use only the the AMD
card for the display.

   A side effect of this is that some Windows updates, as well as AMD
driver updates, end up switching back to the virtual cirrus card; when
that happens I need to use VNC to get in and repair it.

   So you'll need to make sure you enable VNC on your VM in case you
need to rescue it.

* I have the motherboard's USB passed-through to the DomU as well (all
actual administration of the host is done via SSH).
     I had to add a flag to allow insecure pass-throughs (I think it's
"permissive=1") because the other peripherals on the motherboard had
shared MTRRs or something.
     I had tried to put in a PCI USB card, but I tried three different
cards and none of them worked correctly when passed-through, so I gave
up on that.

Those are the main things I remember encountering with regard to
setting it up and keeping it running.
(3) The other VMs aren't very heavy load (they're just some internal
websites used to trigger Smart Home stuff), so I've never had to deal
with prioritization.

(4) I don't know what the performance loss is, but I do know that the
system can handle itself pretty well.  Games that depend heavily upon
the GPU -- DOOM 2016, Wolfenstein: The New Order, etc -- run great
under my R250.   Games that are very highly CPU-bound, like some Unity
engine games (Dreamfall Chapters comes to mind) don't do as well;
however, that might just be because my CPU, an i7-4790S, is a low-TDP
version with a lower-than-average clock speed to keep the temperature
down; for all I know, Dreamfall Chapters would have run poorly even
without the VM interception.

-- Stevie-O
Real programmers use COPY CON PROGRAM.EXE

-- Stevie-O
Real programmers use COPY CON PROGRAM.EXE
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