Re: (v2) Design proposal for RMRR fix

["Tian, Kevin" <kevin.tian@intel.com>]

> From: George Dunlap
> Sent: Thursday, January 08, 2015 8:55 PM
> 
> On Thu, Jan 8, 2015 at 12:49 PM, George Dunlap
> <George.Dunlap@eu.citrix.com> wrote:
> > If RMRRs almost always happen up above 2G, for example, then a simple
> > solution that wouldn't require too much work would be to make sure
> > that the PCI MMIO hole we specify to libxc and to qemu-upstream is big
> > enough to include all RMRRs.  That would satisfy the libxc and qemu
> > requirements.
> >
> > If we then store specific RMRRs we want included in xenstore,
> > hvmloader can put them in the e820 map, and that would satisfy the
> > hvmloader requirement.
> 
> An alternate thing to do here would be to "properly" fix the
> qemu-upstream problem, by making a way for hvmloader to communicate
> changes in the gpfn layout to qemu.
> 
> Then hvmloader could do the work of moving memory under RMRRs to
> higher memory; and libxc wouldn't need to be involved at all.
> 
> I think it would also fix our long-standing issues with assigning PCI
> devices to qemu-upstream guests, which up until now have only been
> worked around.
> 

could you elaborate a bit for that long-standing issue?

Thanks
Kevin