From mboxrd@z Thu Jan  1 00:00:00 1970
From: George Dunlap <george.dunlap@eu.citrix.com>
Subject: Re: GPU passthrough issue when VM is configured with 4G
 memory
Date: Tue, 16 Apr 2013 13:37:03 +0100
Message-ID: <516D45EF.9040608@eu.citrix.com>
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To: =?ISO-8859-1?Q?Pasi_K=E4rkk=E4inen?= <pasik@iki.fi>
Cc: Stefano Stabellini <Stefano.Stabellini@eu.citrix.com>, "xudong.hao@intel.com" <xudong.hao@intel.com>, Yanqiangjun <yanqiangjun@huawei.com>, Luonengjun <luonengjun@huawei.com>, Wangzhenguo <wangzhenguo@huawei.com>, Yangxiaowei <xiaowei.yang@huawei.com>, "Gonglei (Arei)" <arei.gonglei@huawei.com>, Anthony Perard <anthony.perard@citrix.com>, "xen-devel@lists.xen.org" <xen-devel@lists.xen.org>, Hanweidong <hanweidong@huawei.com>, "xiantao.zhang@intel.com" <xiantao.zhang@intel.com>
List-Id: xen-devel@lists.xenproject.org

On 15/04/13 22:22, Pasi K=E4rkk=E4inen 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 >=3D 0xe0000000 ) {
>>>>          above_4g_mem_size =3D ram_size - 0xe0000000;
>>>>          below_4g_mem_size =3D 0xe0000000;
>>>>      } else {
>>>>          above_4g_mem_size =3D 0;
>>>>          below_4g_mem_size =3D ram_size;
>>>>      }
>>> The guys at Intel sent a couple of patches recently to fix this issue:
>>>
>>> http://marc.info/?l=3Dxen-devel&m=3D136150317011027
>>> http://marc.info/?l=3Dqemu-devel&m=3D136177475215360&w=3D2
>>>
>>> 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?