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

[George Dunlap <george.dunlap@xxxxxxxxxxxxx>]

On 15/04/13 22:22, Pasi Kärkkäinen wrote:
> On Tue, Mar 26, 2013 at 09:37:53AM +0000, Hanweidong wrote:
> > > > HVM_BELOW_4G_RAM_END is f0000000. If we change HVM_BELOW_4G_RAM_END
> > > to e0000000,
> > > > Which it's consistent with hvmloader when assigning a GPU, and then
> > > guest worked
> > > > for us. So we wondering that xen_ram_init in QEMU should be
> > > consistent with
> > > > hvmloader.
> > > >
> > > > In addition, we found QEMU uses hardcode 0xe0000000 in pc_init1() as
> > > below.
> > > > Should keep these places handle the consistent mmio hole or not?
> > > >
> > > >      if (ram_size >= 0xe0000000 ) {
> > > >          above_4g_mem_size = ram_size - 0xe0000000;
> > > >          below_4g_mem_size = 0xe0000000;
> > > >      } else {
> > > >          above_4g_mem_size = 0;
> > > >          below_4g_mem_size = ram_size;
> > > >      }
> > > The guys at Intel sent a couple of patches recently to fix this issue:
> > >
> > > http://marc.info/?l=xen-devel&m=136150317011027
> > > http://marc.info/?l=qemu-devel&m=136177475215360&w=2
> > >
> > > Do they solve your problem?
> > These two patches didn't solve our problem.
> Any updates on this? It'd be nice to get this fixed before Xen 4.3.
It looks like the qemu guys didn't like the patch; they said there was 
already an interface to get this information.  I didn't see whether Xu 
Dong followed that up or not.
I'm going to list this as a bug, hopefully we can get it sorted out.

 -George


> Thanks,
>
> -- Pasi
>   
> > --weidong
> >
> > > Xudong and Xiantao,
> > > are you going to send an update of the second patch to QEMU?

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