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Re: [Qemu-devel] [PATCH v2 0/6] x86: Physical address limit patches
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH v2 0/6] x86: Physical address limit patches |
Date: |
Tue, 5 Jul 2016 13:41:50 +0100 |
User-agent: |
Mutt/1.6.1 (2016-04-27) |
* Michael S. Tsirkin (address@hidden) wrote:
> On Tue, Jul 05, 2016 at 12:59:42PM +0200, Paolo Bonzini wrote:
> >
> >
> > On 05/07/2016 12:06, Michael S. Tsirkin wrote:
> > > > -m 2G,slots=16,maxmem=2T
> > > >
> > > > On a host with a 39bit physaddress limit do you error
> > > > on that or not? I think oVirt is currently doing something
> > > > similar to that, but I'm trying to get confirmation.
> > >
> > > That would only be a problem since pci is allocated above
> > > maxmem so 64 bit pci addresses aren't accessible.
> > > With my proposal we can actually force firmware to avoid
> > > using 64 bit memory for that config.
> > > Will work better than today.
> >
> > So you would remove completely the 64-bit _CRS in this case?
>
> Yes.
>
> > How do you handle migration in the above scenario from say 46bit host to
> > 39bit host, where the firmware has mapped (while running on the source)
> > a 64-bit BAR above the destination's maximum physical address?
> >
> > Thanks,
> >
> > Paolo
>
> Again management would specify how much 64 bit pci space firmware should use.
> If more is specified than host can support we can error out.
What stops the guest OS mapping PCI stuff high up - however much you change
the firmware?
Dave
>
> --
> MST
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- Re: [Qemu-devel] [PATCH v2 6/6] x86: Add sanity checks on phys_bits, (continued)
- Re: [Qemu-devel] [PATCH v2 0/6] x86: Physical address limit patches, Michael S. Tsirkin, 2016/07/04
- Re: [Qemu-devel] [PATCH v2 0/6] x86: Physical address limit patches, Dr. David Alan Gilbert, 2016/07/05
- Re: [Qemu-devel] [PATCH v2 0/6] x86: Physical address limit patches, Paolo Bonzini, 2016/07/05
- Re: [Qemu-devel] [PATCH v2 0/6] x86: Physical address limit patches, Michael S. Tsirkin, 2016/07/05
- Re: [Qemu-devel] [PATCH v2 0/6] x86: Physical address limit patches, Paolo Bonzini, 2016/07/05
- Re: [Qemu-devel] [PATCH v2 0/6] x86: Physical address limit patches, Michael S. Tsirkin, 2016/07/05
- Re: [Qemu-devel] [PATCH v2 0/6] x86: Physical address limit patches,
Dr. David Alan Gilbert <=
- Re: [Qemu-devel] [PATCH v2 0/6] x86: Physical address limit patches, Michael S. Tsirkin, 2016/07/05
Re: [Qemu-devel] [PATCH v2 0/6] x86: Physical address limit patches, Daniel P. Berrange, 2016/07/05