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

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

In addition, we found QEMU uses hardcode 0xe0000000 in pc_init1() as
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:


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.



-- Pasi

Xudong and Xiantao,
are you going to send an update of the second patch to QEMU?

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