Re: [Xen-devel] GPU passthrough issue when VM is configured with 4G memory

[Matthias <matthias.kannenberg@xxxxxxxxxxxxxx>]

Yes, normal PCI Passthrough works fine with like 5GB of Ram (tested
with 3 USB controller and 1 Audio device).

But the moment I use vga passthrough (using an AMD card with secondary
passthrough), vnc stays black all the way till i get the bluescreen.

2013/3/5 Pasi Kärkkäinen <pasik@xxxxxx>:
> On Tue, Mar 05, 2013 at 03:21:46PM +0100, Matthias wrote:
>> I can recreate the issue:
>>
>> Whereas xen-unstable does VGA passthrough fine with more then 4G RAM
>> with traditional qemu, xen's qemu  upstream does only work with memory
>> < 4G.
>>
>
> Does "normal" PCI passthrough work with qemu upstream + xen-unstable and >4G 
> RAM?
> Say, a NIC, or a USB controller, or a soundcard.
>
> -- Pasi
>
>>
>> 2013/3/5 Pasi Kärkkäinen <pasik@xxxxxx>:
>> > On Tue, Mar 05, 2013 at 12:44:36PM +0000, Hanweidong wrote:
>> >> >
>> >> > >    I have tried to passthrough GPU card(Nvidia quadro 4000) on the 
>> >> > > latest
>> >> > Xen
>> >> > >    unstable version (QEMU is using Qemu-upsteam-unstable, not 
>> >> > > traditional
>> >> > >    Qemu). This issue as below:
>> >> > >
>> >> >
>> >> > I don't think qemu-upstream has GPU/VGA passthrough support yet.
>> >>
>> >> Qemu-upstream already supports GPU/VGA pass-through.
>> >>
>> >
>> > Really? With Xen?
>> > I haven't seen the patches..
>> >
>> >> If we configure VM memory with 3G, GPU pass-through works well.
>> >>
>> >
>> > Right..
>> >
>> >
>> >> >
>> >> >
>> >> > >           Windows7 64-bit guest will blue screen when GPU passthrough
>> >> > >    configure 4g memory,blue screen code is 50, and SUSE 11 64-bit 
>> >> > > guest
>> >> > will
>> >> > >    always stay at the grub screen.  I noticed that it will relocate 
>> >> > > RAM that
>> >> > >    overlaps PCI space in pci_setup()(tools/hvmloader/pci.c). If VM 
>> >> > > memory
>> >> > is
>> >> > >    configured with 3G, it won't cause relocate RAM that overlaps PCI 
>> >> > > space
>> >> > in
>> >> > >    pci_setup(), and GPU pass-through is no problem. So it seems this 
>> >> > > issue
>> >> > is
>> >> > >    related to "relocate RAM" in pci_setup().
>> >> > >
>> >> > >           In the failure case (VM memory is 4G), I used "memtest" to
>> >> > check
>> >> > >    memory of the VM which configured with more than 4G memory, the 
>> >> > > last
>> >> > 256M
>> >> > >    has errors.
>> >> > >
>> >> > >
>> >> > >
>> >> > >    BTW, Xen 4.1.2 doesn't have this issue.
>> >> > >
>> >> >
>> >> > I assume with Xen 4.1.2 you're using qemu-traditional.. ?
>> >>
>> >>  Yes, we tried Xen 4.1.2 with qemu-traditional.
>> >>
>> >> >
>> >> > Try using qemu-traditional also with xen-unstable.
>> >> >
>> >>
>> >> OK, we will have a try. But seems it's not qemu's problem, we can make 
>> >> GPU pass-through succeed if we didn't do
>> >> XENMAPSPACE_gmfn_range hypercall in pci_setup() with 4G memory.
>> >>
>> >
>> > Yep. Please send patches when you figure it out!
>> >
>> >
>> > -- Pasi
>> >
>> >
>> >
>> >> --Weidong
>> >>
>> >> > -- Pasi
>> >> >
>> >> > >
>> >> > >
>> >> > >    Any ideas about this issue? Thanks in advance.
>> >> > >
>> >> > >
>> >> >
>> >> > > _______________________________________________
>> >> > > Xen-devel mailing list
>> >> > > Xen-devel@xxxxxxxxxxxxx
>> >> > > http://lists.xen.org/xen-devel
>> >>
>> >
>> > _______________________________________________
>> > Xen-devel mailing list
>> > Xen-devel@xxxxxxxxxxxxx
>> > http://lists.xen.org/xen-devel

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