On Mon, Apr 27, 2009 at 04:00:30PM +0200, Christian Borntraeger wrote: > Am Monday 27 April 2009 14:31:36 schrieb Michael S. Tsirkin: > > Add optional MSI-X support: use a vector per virtqueue with > > fallback to a common vector and finally to regular interrupt. > > Teach all drivers to use it. > > > > I added 2 new virtio operations: request_vqs/free_vqs because MSI > > needs to know the total number of vectors upfront. > > > > Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx> > > I dont know, if that is feasible for MSI, but the transport(virtio_pci) should > already know the number of virtqueues, which should match the number of > vectors, no? I think no, the transport can find out the max number of vectors the device supports (pci_msix_table_size), but not how many virtqueues are needed by the driver. As number of virtqueues <= number of vectors, we could pre-allocate all vectors that host supports, but this seems a bit drastic as an MSI-X device could support up to 2K vectors. > In fact, the transport has to have a way of getting the number of virtqeues > because find_vq returns ENOENT on invalid index numbers. > > Christian So again, I think this is an upper bound supported by host. Right? -- MST -- 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
