A query on frame buffers

[Prasad Joshi]

On Fri, Jan 7, 2011 at 7:24 PM, Konrad Rzeszutek Wilk
<konrad.wilk at oracle.com> wrote:
> On Fri, Jan 07, 2011 at 05:47:59PM +0000, Prasad Joshi wrote:
>> 2011/1/7 Konrad Rzeszutek Wilk <konrad.wilk at oracle.com>:
>> >> > The errors
>> >> >
>> >> > [    3.778476] [drm:r100_ring_test] *ERROR* radeon: ring test failed
>> >> > (sracth(0x15E4)=0xCAFEDEAD)
>> >> > [    3.781010] [drm:r100_cp_init] *ERROR* radeon: cp isn't working (-22).
>> >> > [    3.782542] radeon 0000:00:04.0: failled initializing CP (-22).
>> >> > [    3.784006] radeon 0000:00:04.0: Disabling GPU acceleration
>> >> >
>> >> > Seem to be disabling GPU functionality. For now, I am interested in
>> >> > Graphics functionality of the ATI card and not GPGPU functionality.
>> >> >
>> >> > I will appreciate if you can help me with some information on solving
>> >> > this problem. Let me know if I should be asking this question on
>> >> > another forum. Please keep me in CC.
>> >>
>> >> Looks like dri-devel material, added to CC.
>> >>
>> >> As a first guess, maybe the system memory pages accessed by the GPU GART
>> >> aren't the same ones intended for this by the VM.
>> >
>> > I actually have patches for that (sorry for the late reply).
>> >
>> > Try:
>> > git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen.git devel/ttm.pci-api.v3

I could access the git repository, but was not able to get those
patches form the repository. Frankly speaking, I don't know how to get
those patches.

>> >
>> > But I am not sure if they would make any difference here. You said
>> > you are using KVM-QEMU - you must also be using an IOMMU? Does the IOMMU
>> > give you any errors?
>> >
>>
>> Yes I want to pass-through the ATI Radeon card to VM in KVM. I have
>> enabled the IOMMU support and it works perfectly alright. I tried
>> passing through a network card it worked.
>>
>> Should I try the patch you suggested?
>
> Go for it. I am still at lost why you would see those errors unless..
> well, what is the DMA code that gets turned on when you run your guest?
> What do you see for 'PCI-DMA' ? Is it bounce buffer or swiotlb?
> How much memory do you pass to the guest? less than 4GB?
>
I am trying these things on Uni server, I will let you know the
answers by tomorrow.

Thanks and Regards,
Prasad