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?
In fact, the transport has to have a way of getting the number of virtqeues
because find_vq returns ENOENT on invalid index numbers.
One thing I thought was to decouple the virtqueue count from the MSI
entry count, and let the guest choose how many MSI entries it wants to
use. This is useful if it wants several queues to share an interrupt,
perhaps it wants both rx and tx rings on one cpu to share a single vector.
So the device could expose a large, constant number of MSI entries, and
in addition expose a table mapping ring number to msi entry number. The
guest could point all rings to one entry, or have each ring use a
private entry, or anything in between.
That saves us the new API (at the expense of a lot more code, but with
added flexibility).
--
error compiling committee.c: too many arguments to function
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