Re: Struggling with PCI-Passthrough

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 11/03/14 10:26, Alexander Brychcy wrote:
> Am 10.03.2014 12:09, schrieb Andrew Cooper:
>> On 10/03/14 09:59, Alexander Brychcy wrote:
>>> Hi,
>>>
>>> I'm currently trying to create a Windows 7 HVM with GPU Passthrough.
>>>
>>> My setup is the following:
>>> CPU:	Xeon E3-1230v3
>>> Board:	Asus P9D-E/4L
>>> RAM:	16GB Kingston from Board QVL
>>> GPU:	Sapphire R9 270X 4GB
>>>
>>> The passthrough itself is working (Tested with Debian Wheezy dom0 on Xen
>>> 4.1, then XenServer 6.2 and now Debian Jessie dom0 on Xen 4.3)
>>>
>>> Under Debian Jessie i was not able to passthrough the USB Controller,
>>> although it appeard at xl pci-assignable-list and i cannot assign more
>>> than 2GB of memory to the HVM.
>>>
>>> The overall problem is, that the HVM starts up and is running fine. But
>>> after a unspecific amount of time the hole system freezes. The cursor in
>>> dom0 still blinking, but no input possible - not even in xen serial
>>> console. I had one run, without a freeze, but the GPU performance was
>>> very poor, so i tried a manual reset. After the HVM reboot the
>>> performance was as expected, but soon the system froze again.
>>>
>>> I'm not sure, if this problem is related to Xen, because i tried to
>>> create the virtual machine with KVM and had the same issue. But i
>>> switched to Xen to get the best performace.
>>>
>>> I will add my config and log files and hope you can help me to get this
>>> setup fully working.
>>>
>>> Kind regards,
>>> Alexander
>> Looking at the serial log, it would appear that Xen has decided to
>> schedule no vcpus whatsoever, and is completely idle.
>>
>> Looking at the 'Q' output, only two vcpus (one from each domain) are not
>> in a blocked state, but no obvious reason for them to be blocked; they
>> are not blocked waiting for events.
>>
>> Are you able to try this with a debug version of Xen?  Perhaps an
>> assertion will be tripped which might give more of a clue.
>>
>> It is certainly interesting that the same behaviour exists with KVM,
>> suggesting it is something to do with hardware interaction, but I can
>> see no obvious reason why Xen is as idle as it is.
>>
>> ~Andrew
>>
> I will try everything to get this machine running, but i won't be able
> test again before the weekend. The nullmodem cable was only borrowed and
> it takes some time for my own to arrive.
>
> Which switches do I have to set during configure to get a debug version?
>
> I will start a new thread on xen-users when everything is set up. Just
> clicked on the wrong mailto when starting this conversation.

I would keep this on Xen-devel, especially if building a debug version
of xen.  My gut feel is that it isn't a xen-users@ problem.

Debug is not a configure option.  from the root of the Xen source tree,
`make -C xen debug=y` (with appropriate -j and cross compile options for
non-standard environments) should make a debug xen/xen.gz.

If this is the same source that your tools are built from, it is save to
just swap out Xen and reboot, to save rebuilding and installing
everything else.

~Andrew