Re: [Xen-users] Xen 4.7.0 graphics pass through problems (Win10, AMD Radeon)

[Peter Milesson <miles@atmos.eu>]

On 2016-09-14 16:49, Jan Beulich wrote:
>>>> On 14.09.16 at 16:04, <miles@atmos.eu> wrote:
>> On 2016-09-14 14:50, Jan Beulich wrote:
>>>>>> On 14.09.16 at 13:34, <george.dunlap@citrix.com> wrote:
>>>> Can you think of anything that's changed between 4.6 and 4.7 that
>>>> would cause the performance problems he's describing when both a video
>>>> card and a usb controller are passed through, but not when only the
>>>> video card is passed through?
>>> Not really, no. Peter - are there any indications of problems in
>>> one or more of the logs (Xen, xl, qemu)? Did you try running a
>>> debug build of all Xen components?
>> No, I did not try a debug build. However, the system seems fairly stable
>> now, only the display driver crashing once, or twice a day. That did
>> occur with Xen 4.6.3 also, but maybe once a week. Looking at the log
>> files, I cannot see anything particular that stands out, except for the
>> domU log.
>>
>> The domU log file qemu-dm-<Name>.log started to contain the following
>> lines after upgrading to 4.7:
>>
>> [00:06.0] xen_pt_bar_read: Error: Should not read BAR through QEMU.
>> @0x0000000000000004
>> [00:06.0] xen_pt_bar_write: Error: Should not write BAR through QEMU.
>> @0x0000000000000000
>>
>> There are only a couple of lines with write, the rest with read. I don't
>> know what significance it's got, but there are around 350 lines every day.
> Looks wrong in any case, but I have no clue whether it's indicative
> of the problem you're having. In any event in the qemu tree in
> hw/xen/xen_pt.h there's an "#ifdef XEN_PT_LOGGING_ENABLED"
> conditional close to the top. Could you make this "#if 1" instead
> (or simply #define XEN_PT_LOGGING_ENABLED in the line above)
> and re-build at least qemu? The log of a subsequent guest run
> should then be quite a bit more helpful in possibly spotting what's
> going wrong to cause those messages.
>
> And then it's of course rather relevant to know what device 00:06.0
> actually is (iirc these are guest BDF values), considering that you're
> passing through more than one.
>
> Jan
>
>
Hi Jan,

I had a look at the guest devices, and Windows says "Standard Enhanced 
PCI to USB Host Controller". Having a look at the Properties, in the 
Device status field is the following message:
---
This device cannot start. (Code 10)

{Operation Failed}
The requested operation was unsuccessful.
---

This USB device wasn't there with Xen 4.6.3. Has it got something to do 
with the new USB passthrough? However, I have tried USB passthrough (xl 
usbctrl-attach), which doesn't work. But that is possibly another problem.

No problem to recompile Xen with the logging flag, if it would be required.

Best regards,

Peter

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
https://lists.xen.org/xen-devel