Re: [Xen-devel] Does xen-4.2.0 support VGA passthrough with the virtual machine created by xl command?

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Thu, Nov 29, 2012 at 07:25:01PM -0600, Dr. Greg Wettstein wrote:
> 
> I was going to get an update back to everyone but got swamped by the
> holiday weekend and a series of hardware failures I had to chase
> after.
> 
> I took advantage of some time over the holiday weekend to chase down
> the passthrough problems and now have it working well on 4.2.0 on all
> kernels up to 3.4.19 using XM.  The original ATI patches have a bug in
> them which causes qemu-dm to core dump on kernels somewhere after
> 2.6.32.x.
> 
> The original patches were bracketing the inb/outb instructions used in
> ati_hw_read()/ati_hw_write with an ioperm() call.  The fix was a
> straight forward replacement of the ioperm() call with a call to
> iopl(3).
> 
> I seem to vaguely remember something about the kernel not properly
> enforcing access controlls on in/out instructions but don't remember
> if that was with a pvops or standard kernel.  In any event the kernel
> behavior changed after 2.6.32.x which triggered the breakage.
> 
> I will post an updated version of the ATI patches under separate cover
> in case anytone else is using them.
> 

Yes please. Thanks!


> 
> We were under some time constraints to get Windows access back working
> with a 'modern' kernel so once things were working reliably with xm I
> didn't get a chance to fiddle with xl.  Given the behavior I saw on
> 2.6.32.x with xl I'm suspicious it may not work.  I'm hoping to get
> back and do some testing early next week.
> 
> I just checked the machine (which is running a Windows session as I
> write this) and dont see any [virtual] references.  This is on 3.4.18
> but I also haven't had the chance to check xl on that kernel.  At
> least a couple of hundred Windows 7 boots have been done with xm so
> 4.2.0 seems solid with that control plane.
> 
> With respect to reservation of the PCI device we have a script which
> unplugs the device and re-plugs it after the Window session
> completes.  The machines are Linux/Windows dual-use so the cards need
> to be active for the Linux sessions.
> 
> The script can be picked up at the following location:
> 
>       ftp://ftp.enjellic.com/pub/xen/run-passthrough
> 
> I will give xl a try later in the weekend with the updated qemu-dm and
> I will report back the results from a more throroughly controlled test
> environment.
> 
> Thanks for the input, have a good weekend.
> 

Thanks!

-- Pasi


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