On Wed, Sep 28, 2011 at 09:30:51PM +0300, Sasha Levin wrote: > On Mon, 2011-09-19 at 17:19 +0930, Rusty Russell wrote: > > On Mon, 19 Sep 2011 09:01:50 +0300, "Michael S. Tsirkin" <mst@xxxxxxxxxx> wrote: > > > On Mon, Sep 19, 2011 at 01:05:17PM +0930, Rusty Russell wrote: > > > > On Sat, 20 Aug 2011 23:00:44 +0300, "Michael S. Tsirkin" <mst@xxxxxxxxxx> wrote: > > > > > On Fri, Aug 19, 2011 at 07:33:07PM +0300, Sasha Levin wrote: > > > > > > Maybe this is better solved by copying the way it was done in PCI itself > > > > > > with capability linked list? > > > > > > > > > > There are any number of ways to lay out the structure. I went for what > > > > > seemed a simplest one. For MSI-X the train has left the station. We > > > > > can probably still tweak where the high 32 bit features > > > > > for 64 bit features are. No idea if it's worth it. > > > > > > > > Sorry, this has been in the back of my mind. I think it's a good idea; > > > > can we use the capability linked list for pre-device specific stuff from > > > > now on? > > > > > > > > Thanks, > > > > Rusty. > > > > > > Do we even want capability bits then? > > > We can give each capability an ack flag ... > > > > We could have, and if I'd known PCI when I designed virtio I might have. > > > > But it's not easy now to map structure offsets to that scheme, and we > > can't really force such a change on the non-PCI users. So I'd say we > > should only do it for the non-device-specific options. ie. we'll still > > have the MSI-X case move the device-specific config, but we'll use a > > linked list from now on, eg. for the next 32 features bits... > > > > Thoughts? > > Rusty. > > What if we create a capability list but place it in the virtio-pci > config space instead of the PCI space? Pls note that virtio-pci config space is io so it is very constrained, we do need to pack it densely. If we want to add a lot of stuff there we probably should move it to memory space. It's slower than io on kvm, but most uses of it aren't on data path. > It'll work fine with non-PCI users and would leave MSI-X as the only > thing that changes offsets (and we could probably deprecate and remove > it at some point in the future). > > -- > > Sasha. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
