Xen project Mailing List

1. I'm using distro packages only. In my first attempt I used Linux Mint 16 (based on Ubuntu 13.10), which is the latest stable release. This is what I'm currently running on my regular setup with Nvidia Quadro for domU and it works fine. It just doesn't work with the AMD 7770.
However, I am not a 100% sure if the Linux Mint install was completely up-to-date. I had installed LM16 some time ago, and I only did some package updates. I may have missed the kernel updates (which aren't applied automatically with updates and need to be done manually).
The error 22 - invalid argument you reported is known to me. In fact, I replied to a similar bug report here. Here a quote from the change log I keep with the VGA passthrough how-to:

30.04.2013 - warning re xen hypervisor release 4.1.3-3ubuntu1.5 upgrade

As I said above, all my packages come from the distributions' stable branch, in this case Ubuntu 13.10 Saucy Salamander (who invents these names?) - I don't think Linux Mint changes anything in these packages.

2. The second trial with Linux Mint 13 (based on Ubuntu 12.04 LTS Precise Pangolin), using the xm toolstack, worked as it should. I was able to shutdown and reboot the domU multiple times without any issue - no slowdown, no instability, solid as a rock. I did not try the xl toolstack with that release, as xl then was still in the diapers.

By the way, I dumped virt-manager because it causes more troubles than it does good. I also searched in vain for a config file.

I believe that Xen 4.1.2 with xm toolstack and an old 3.2 kernel is still the best way to get VGA passthrough running. The migration to xl introduced some issues, so did some of the security patches (the XSA patches). So, when you got a working system, don't upgrade if you can help it.

On Thursday, March 13, 2014 10:49 PM, Gordan Bobic <gordan@xxxxxxxxxx> wrote:

On 03/13/2014 08:33 PM, H. Sieger wrote:
> I spent the last 8 hours testing VGA passthrough with a AMD Radeon 7770
> card. Here the setup:
>
> Hardware: Asus Sabertooth X79 with latest BIOS and VT-d enabled; i7
> 3930K CPU; Sapphire Radeon 6450 for dom0, Sapphire Radeon 7770 for domU.
>
> 1st trial - Linux Mint 16 64 bit with kernel 3.11.0-18 and Xen 4.3.0;
> Windows 7 Pro 64 bit; both installed on external USB3 disk:
>
> In short, a disaster. I first tried the xl toolstack I was using with my
> regular configuration (same m/b and CPU, but AMD Radeon 7770 for dom0
> and Nvidia Quadro 2000 for domU).
> I tried to make a new Windows installation in domU. After each shutdown
> of the domU I had to reboot the whole machine, else I would get libxl...
> errors and nothing. dom0 wouldn't even shut down, had to hard reset. I
> somehow managed to install Windows, but once I tried to install the
> graphics driver for the AMD card Windows sooner or later gave me a blue
> screen.

Did you build from source or use distro packages? If you are using the
distro packages it is possible your distribution's packages are broken
or old enough to contain regressions.

> Next I tried with xm. I started from scratch, setting up a new Windows
> LVM volume. xm create ... failed with "error 22". That sounds familiar.
> I had the same issue with my regular Nvidia setup some time ago with Xen
> 4.1.3. But I thought that by Xen 4.3 this was fixed?!

I'm sure I remember this bug and it was due to a regression at some
point. Ah, here it is:

http://xen.crc.id.au/bugs/view.php?id=5

Regression introduced in XSA-46.

> In the bug report someone suggests to pass through only the first
> function of the graphics card, in my case PCI ID 02:00.0, and not
> specify the second (HDMI audio) function 02:00.1. I tried but no luck.
> Just to make sure, removed the graphics card from the PCI passthrough
> devices and only left a USB controller to pass through, which worked!
>
> Summary: Xen 4.3.0 still has some of the old bugs that I that had gone
> long ago. Or is that a kernel issue?

Where do your packages/binaries come from?

> 2nd trial - Linux Mint 13 64 bit with kernel 3.2 and Xen 4.1.2; Windows
> 7 Pro 64 bit; both installed on external USB3 disk:

I vaguely recall issues with a number of kernels. I'm currently running
with 3.9.9 (I should have upgrade to 3.12 by now but 3.9.9 works without
any issues for me so I am finding it hard to persuade myself to try
upgrading.)

> I installed the long term release Linux Mint 13 that worked well when I
> started out with Xen VGA passthrough. After installation and upgrading
> all packages and the kernel, I installed Xen and then downgraded using
> "Force version" in Synaptic to the earliest Xen release available in the
> repos, which was 4.1.2 if I remember correctly.
> This time I only used xm. Installation went smooth, no hickups no
> nothing after multiple reboots of Windows. Passthrough works just fine
> with the AMD Radeon 7770. I ran the WEI, both prior and after installing
> the GPLPV drivers in Windows - it made no difference - 5.9 lowest score
> for disk (a 2.5" HDD attached via USB3), 2D and 3D graphics are 7.5,
> memory 7.9 (with 8GB for Windows), and CPU 7.8 (I gave it 8 of 12
> VCPUS). I even installed the Unigine demo and benchmark - it ran fine
> though the 7770 is really not up for it with 21fps.
>
> Summary: Xen 4.1.2 with an old 3.2 kernel works perfect with xm and VGA
> passthrough.

Does it continue working across domU reboots?

> To me this looks like some ancient bugs are still not fixed (with regard
> to xm), and probably never will since it's been deprecated. The sad
> story, however, is that xl has its own serious problems with VGA
> passthrough.

It works for me (Xen 4.3.0 with xl, kernel 3.9.9).

> Whatever it is, it's not an AMD driver issue. The problems start long
> before I even managed to install the AMD driver.

And with 4.1.2 you can reboot the domU multiple times without it
resulting in massive slow-down, BSODs, or the card not coming up?

> Hope someone from Xen development has a look at this. Although this
> means reconfiguring my hardware, I'd be happy to help in debugging if
> anyone is willing to try and fix it.

Gordan

Re: [Xen-users] VGA passthrough with Xen 4.3 and xl toolstack - performance degradation resolved?