Re: Bug: Limitation of <=2GB RAM in domU persists with 4.3.0

[Gordan Bobic <gordan@bobich.net>]

On 07/31/2013 06:56 PM, Andrew Cooper wrote:
> On 31/07/13 18:53, George Dunlap wrote:
>> On Fri, Jul 26, 2013 at 2:11 PM, Gordan Bobic <gordan@bobich.net> wrote:
>>>> Now that is intereting - if this makes the memory holes the same between
>>>> the guest and the host, does it also implicitly vBAR=pBAR?
>>>
>>> Another thing that occurred to me might be useful to check - it is
>>> pretty easy to modify the BAR size on Nvidia cards. The defaults are
>>> 64MB and 128MB for the two BARs. They can be made much, much larger,
>>> and there is often advantage to enlarging them to at least be equal to
>>> VRAM size. Soooooo... If I boost the BAR from 128MB to 2GB, being a
>>> 64-bit BAR, it might make the BIOS do the sane thing and map it above
>>> 4GB. With the other BAR also suitably enlarged and it being done on
>>> the second GPU as well, there is no obvious option but to map them
>>> above 4GB (unless the BIOS is broken, which it may well be, in
>>> which case all bets are off).
>>>
>>> Which may just alleviate the memory issue if not completely fix
>>> the problem.
>>>
>>> Will try this and see what happens.
>> I believe XenServer has a patch that allows the toolstack (in this
>> case xapi) to set the default size of the MMIO hole.  Andrew, did that
>> ever make it upstream?
>>
>> Unfortunately, it is unlikely to work with upstream qemu until we fix
>> the memory relocation issue...
>>
>
> I believe it did - the patch does not exist in our patch queue any more.

Can anyone point me at the relevant commit / docs on this patch?

Gordan