Re: [Xen-users] VGA Passthru

["Nick Couchman" <Nick.Couchman@xxxxxxxxx>]

>>> On 2010/05/11 at 03:47, <destinyqq@xxxxxxxxxxx> wrote: 
> Hi Nick Couchman
> 
>     Did you mean like this:  we will not see any VGA output and can not 
> login to desktop,if add "xen-pciback.hide=(00:02.0)" to grub ?

Not exactly, but kind of.  Initially, with that option, things will display 
just fine; however, once you start your domU and it claims the video card, you 
will lose your ability to use the video card in dom0.  There may be a way to 
reclaim the video card after your HVM domU is shut down, but I don't know what 
that is.  The bottom line is that only one domain can use a PCI device at a 
time - so, when the domU grabs the VGA device, dom0 cannot use it any longer.

Also, if there is a kernel module loaded that uses any of the PCI cards you 
wish to forward through to the domU, you have to unload the module, first, 
before the card can be passed through.

> 
>     I can't passthrough Q45-IGD to hvm.
> 
>     I add "xen-pciback.hide=(00:02.0)" to grub, but i can login to desktop, 
> and i can see 00:02.0 in "xm pci-list-assignable-devices".
> 
>     Then,I create hvm, the monitor input  disappear. But i can reboot Dom0 
> from Keyboard.

Yes, you should see the display disappear for your dom0, but you should see the 
HVM domU display appear.  If the card is dual-headed, you may need to try 
switching over to the other video port.  Also, make sure you forward through 
all of the PCI devices associated with the card - on my Optiplex 755, I forward 
00:02.0 and 00:02.1 through.  And, make sure you have gfx_passthru enabled.

The keyboard issue is one that I haven't found a great way around.  What I 
ended up doing is making my dom0 "headless" and using either SSH or a serial 
console to access dom0.  I then assign the graphics card and all of the USB PCI 
devices, as well as the sound card, to the HVM domU so that I can use those 
devices there.  For what I'm trying to do - run Xen transparently under 
Windows, so that my engineers can use a familiar interface, but I can use their 
machines for other stuff - this works perfectly fine.  Other folks have 
suggested purchasing an additional PCI or PCIe USB or PS/2 card that will allow 
you to hook up a second keyboard/mouse/etc. to the machine.

-Nick



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