Re: [Xen-devel] [BUG] Xen grabs wrong VGA at VM boot

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 16.10.14 at 09:45, <u56237z@xxxxxxxxxxx> wrote:
> My motherboard is a SuperMicro H8DGi/F with 2x opterons 6140, an onboard 
> Matrox G200 and a discrete Quadro 4000.
> 
> Dom0 is Ubuntu server 14.04 LTS with xen 4.4, XL toolstack
> DomU is HVM win7 Pro x64,
> 
> I have 2 monitors, one is connected to the Quadro, the other to the onboard 
> G200, Bios have been set to boot from the Matrox G200 and the integrated 
> Matrox is the one I use for Dom0 control.
> 
> I had to setup the Quadro as the primary adapter, (gfx_passthrough = 1) 
> otherwise the NV drivers in win7 would randomly (and pretty easily) crash 
> even after trivial operations like a window resize. If insted the Quadro is 
> the primary adapter, there is no problem whatsoever.
> 
> When the virtual machine is started, it erroneously boots using the montor 
> connected to the onboard G200, even if such video card is never referenced in 
> the VM config file.
> 
> Xen keeps on using the onboard Matrox until the Windows logo shows up (more 
> or less in the middle of Windows loading process), then it switches to the 
> Quadro.
> 
> Keyboard and mouse also seem to be PCI passed-through only after the Windows 
> logo shows up.
> 
> This is  annoying because:
> 
> a) Im left with no Dom0 control monitor.
> b) the onboard Matrox is not reset after guest shutdown, so I have to SSH to 
> get control of the system or type without seeing anything.
> 
> Is there a way to prevent Xen from using the onboard Matrox at VM boot, or 
> at least a way to reset the Matrox after guest shutdown?

I think with all of the above this is the wrong question to ask. Instead
it needs to be understood why there is this mix up of who uses which
card. In particular the guest absolutely should not use a device that
it isn't assigned. I'm kind of guessing this is because the tool stack
blindly enables legacy VGA pass-through when passing through a gfx
card (not so long ago pointed out in the context of some patches
copying this to yet another place). What device class do both of your
cards surface (a sufficiently verbose invocation of lspci should tell you)?

Jan


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