Messages in this thread | | | From | Rusty Russell <> | Subject | Re: [PATCH RFC] virtio-pci: support config layout in BAR1 | Date | Fri, 07 Jun 2013 11:43:01 +0930 |
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"Michael S. Tsirkin" <mst@redhat.com> writes: > Some setups don't support enabling BAR0 (IO BAR). Reasons range from CPU > limitations (e.g. on some powerpc setups) to architecture limmitations > (e.g. a setup with >15 PCI bridges, with one virtio device behind each, > on x86). > > PCI Express spec made IO optional, so future guests will disable IO for > a device in more and more configurations. > > This patch makes it possible for host to mirror the config in BAR1, such > that these setups can work properly. > > Guests with old drivers can't be fixed, they will continue to work as > well (or as bad) as they did previously. For this reason, changing > revision id appears unnecessary - it would break setups that previously > worked, partially. > > Future work on re-organizing layout won't conflict with this patch - it > can use a different BAR or put config at an offset, or update revision. > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Since QEMU won't support this, I think we'll have to wait for the PCI capabilities, ie. the virtio spec 1.0.
Cheers, Rusty.
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