Re: [PATCH 2/5] virtio_net: Add a virtqueue for outbound control commands

Mark McLoughlin
2009-01-19T09:32:50Z

On Fri, 2009-01-16 at 14:13 -0700, Alex Williamson wrote:
> This will be used for RX mode, MAC filter table, VLAN filtering, etc...
>
> The control transaction consists of one or more "out" sg entries and
> one or more "in" sg entries. The first out entry contains a header
> defining the class and command. Additional out entries may provide
> data for the command. The last in entry provides a status response
> back from the command.
>
> Virtqueues typically run asynchronous, running a callback function
> when there's data in the channel. We can't readily make use of this
> in the command paths where we need to use this. Instead, we kick
> the virtqueue and spin. The kick causes an I/O write, triggering an
> immediate trap into the hypervisor.
>
> Signed-off-by: Alex Williamson <alex.williamson@hp.com>

Acked-by: Mark McLoughlin <markmc@redhat.com>

Cheers,
Mark.