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

[Andrew Bobulsky <rulerof@xxxxxxxxx>]

On Wed, May 22, 2013 at 11:17 AM, Gordan Bobic <gordan@xxxxxxxxxx> wrote:

On Tue, 21 May 2013 04:09:25 +0000, Hanweidong <hanweidong@xxxxxxxxxx> wrote:

-----Original Message-----
From: Gordan Bobic [mailto:gordan@xxxxxxxxxx]
Sent: 2013å5æ21æ 2:43
To: George Dunlap
Cc: Hanweidong; Stefano Stabellini; xudong.hao@xxxxxxxxx; Yanqiangjun;
Luonengjun; Wangzhenguo; Yangxiaowei; Gonglei (Arei); Anthony Perard;
xen-devel@xxxxxxxxxxxxx; xiantao.zhang@xxxxxxxxx
Subject: Re: [Xen-devel] GPU passthrough issue when VM is configured
with 4G memory

I'd also like to stress this is not only an issue for > 4GB of RAM in
domU - I am seeing the issue with > 2GB of RAM in domU.

What's the total mmio size of you domU?

How can I find that out?

When RAM of domU overlaps
with pci_mem_start, hvmloader will relocate RAM, and it will cause
problem due to hvmloader and QEMU don't setup the memory layout
consistently. I suspect the mmio size of your domU is close to 2GB.
When you configured RAM > 2G, then RAM of your domU overlapped with
pci_mem_start, and resulted in failure.

Is there a way to force a hole between, say, 2GB and 4GB explicitly
to avoid the PCI memory being clobbered?

Gordan

Â

I'll second that question!

Â

Gordan,Âone thing IÂdidn't think of until now: the card I was having trouble with, a Radeon 6990, is a 4GB card, laid out asÂtwo 2GB GPUs. The card with which I don't have issues (aside from the occasional need to reboot the whole system toÂget it to work right),Âa Radeon 5850, is a 1GB card. If as this thread has suggested, along with what I've read about the PCI Hole, the memory on the GPU determines the "clobber size" (yes I made that term up :P), when I get back home (I'm onÂvacation)ÂI'd love to try myÂluck at PCI Hole remapping.

Â

-Andrew

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel