Re: PCI hole resize support for 4.5? If not, workaround?

[Don Slutz <dslutz@verizon.com>]

On 10/20/14 13:14, Steve Freitas wrote:
> On 10/20/2014 6:06, Don Slutz wrote:
>> On 10/18/14 02:17, Steve Freitas wrote:
>>> Hi all,
>>>
>>> I'm suffering from bug 28 [1], unable to assign more than 3.5 gigs 
>>> of RAM to my Windows VM while using VGA passthrough. This is a 
>>> showstopper for me.
>>>
>>> Since #28 is still listed as up for grabs for 4.5 [2], I assume a 
>>> fix is not likely to make it in. However, a message from Ian [3] 
>>> indicated that a workaround was available at some point. Will a 
>>> workaround be offered for 4.4 or 4.5?
>>>
>>
>> Adding the patch:
>>
>> http://lists.xenproject.org/archives/html/xen-devel/2014-10/msg01447.html 
>>
>>
>> to 4.5-unstable
>>
>> and adding
>>
>> mmio_hole_size = 536870912
>>
>> to your .xfg should allow you to use more memory (the number above
>> is .5 gig, which should work based on 3.5 gigs working).
>
> Hi Don!
>
> Thanks for your reply and the patch, my searches didn't turn up your 
> post. Any idea if I'll run into trouble trying to apply this to 4.4.1?

This does require a changed QEMU.  QEMU 2.1 (2.1.2 is the current 
released version)
or the QEMU for Xen 
(http://xenbits.xen.org/git-http/qemu-upstream-unstable.git) in
4.5 will work.

> I'd like to stick with (minimally modified) distro packages if 
> possible, and Debian Jessie is on 4.4.1. And any feeling for whether 
> this will make it into 4.5?

I think it still has a good chance.  Just posted v8, name changed from 
mmio_hole_size
to mmio_hole and the units changed from bytes to MBYTES.  So with v8 you
say:

mmio_hole = 512


> Sure would be nice to see this problem fixed for good.

The change to 4.5 is not a complete fix, but a good 1st step.

    -Don Slutz

>
> Thanks again.
>
> Steve
>