Re: [Xen-devel] Problem: Pattern with vertical colored lines on the dom0 screen

[Dietmar Hahn <dietmar.hahn@xxxxxxxxxxxxxx>]

Am 23.09.2010 schrieb Dietmar Hahn:
> 
> What I wanted to say is, I don't need a linux kernel to reproduce the problem!
> With the argument vga=mode-0x314 on the Xen command line the screen gets
> patterned while booting only the hypervisor.

I added some tracer in the hypervisor and found that the screen gets patterned
when calling iommu_enable_translation() for the graphics device.

...
(XEN) [VT-D]dmar.c:694: found ACPI_DMAR_DRHD:
(XEN) [VT-D]dmar.c:398:   dmaru->address = fed91000
(XEN) [VT-D]dmar.c:334:   endpoint: 0:2.0
...
(XEN) [VT-D]iommu.c:1097: drhd->address = fed91000 iommu->reg = ffff82c3fff57000
...
(XEN) [VT-D]iommu.c:709: iommu_enable_translation: iommu->reg = ffff82c3fff57000
  -> Here the screen gets patterned after setting the DMA_GCMD_TE bit.

My test machine is a laptop with a Intel cpu "i5 M540" and a "Intel QM57"
chipset.
If anybody owns such a hardware and VT-d is working with the graphics device
then please set iommu=verbose on the Xen command line and send me the
(XEN)... logging of the serial console or "xm dmesg" output.
Thanks.

Dietmar.

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