Re: [Xen-devel] Experimental results for VGA passthrough

["Beng Heng, Ng" <bengheng@xxxxxxxxxxxxxx>]

I noticed that Xen does not boot if only the Intel IGD is present and
selected, i.e. only one graphics device.

Also, I'm not able to get high resolution if I passthrough Intel IGD and
install the Intel Graphics Media Accelerator driver. Ironically, I can
get higher resolution and color if I remove the driver. Has anyone
encountered similar observations before?

- Beng Heng

djmagee@xxxxxxxxxxxx wrote:
> The DQ45CB does not have enough PCI Express lanes to drive the IGD and a
> x16 graphics card at the same time.
>  
> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
> [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Beng Heng,
> Ng
> Sent: Thursday, June 04, 2009 11:09 AM
> To: xen-devel
> Subject: [Xen-devel] Experimental results for VGA passthrough
> 
> Hi,
> 
> I tried patching Xen 3.4 Testing c/s 19628 with vga passthrough code
> (less HID passthrough), and did some tests. I made some modifications in
> pci_setup to skip loading the emulated VGA bios and pci_load_option_roms
> to load the passthrough VGA bios. My setup uses Intel DQ45CB and ATI
> HD2600XT.
> 
> The BDFs for the relevant devices are:
> Intel IGD  00:02.0
> ATI gfx    01:00.0, 01:00.1
> There's 2 BDFs for ATI because one of them is for the Audio. Both have
> to be passed through simultaneously.
> 
> In the first scenario, Intel IGD is set up as the primary for Dom0. The
> ATI gfx is passed through to DomU. Interestingly, it is the screen that
> is connected to Intel's output that displays DomU (albeit with few
> colors and low resolution). However, in the Device Manager, ATI is
> reported. I believe this is because Intel's address space is being
> mapped, instead of ATI's. Shutting down DomU does not return the display
> to Dom0. The display remains at the last screen showing DomU shutting
> down. Except for the shutting down phase, I've recorded the observations
> in the first attachment.
> 
> In the second scenario, Intel IGD is passed through to DomU. The ATI gfx
> is thus absent. However, when DomU is booted, there is an IOMMU page
> fault. This is shown in the second attachment starting from Line 659.
> The system subsequently hangs. Does anyone have an explanation to what's
> going on in this case?
> 
> So, VGA passthrough works, but seems extremely flaky. Any
> comments/suggestions to correct the problems observed will be greatly
> appreciated.
> 
> Thanks.
> 
> - Beng Heng


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel