Re: [virtio] [PATCH] virtio-ccw: add adapter interrupt support

[Cornelia Huck <cornelia.huck@de.ibm.com>]

On Wed, 16 Oct 2013 10:45:22 +1030
Rusty Russell <rusty@au1.ibm.com> wrote:

> Cornelia Huck <cornelia.huck@de.ibm.com> writes:
> > On Tue, 15 Oct 2013 14:13:58 +1030
> > Rusty Russell <rusty@au1.ibm.com> wrote:
> >
> >> Cornelia Huck <cornelia.huck@de.ibm.com> writes:
> >> > Specify a new channel command to set up two-stage indicators as needed
> >> > for adapter interrupts and describe how adapter interrupts are used
> >> > for notifications.
> >> 
> >> Since this presumably isn't in the current implementation, should there
> >> be a legacy section talking about what happens if it's not supported?
> >> Or is that implied and I missed it?
> >
> > As a device will reject any channel command it doesn't know, we should
> > be fine. I'll add a legacy section though; a transitional driver should
> > just fall back to classic indicators.
> 
> To make sure I understand correctly: a non-legacy device MUST support
> this, right?  So a non-transitional driver can count on it?  (I guess
> the command might fail for other reasons, so it's still nice for the
> driver to fall back, but not compulsory).

I don't think we win anything if a device stops implementing classic
indicators. Configuration-change indicators still use the same
mechanism, after all.

> 
> Cheers,
> Rusty.