Re: [virtio-comment] [PATCH] Update VIRTIO_F_EVENT_IDX throughout

[Cornelia Huck <cohuck@redhat.com>]

On Fri, 30 Apr 2021 09:27:55 -0700
Joel Nider <joel@nider.org> wrote:

> On 2021-04-30 4:27 a.m., Cornelia Huck wrote:
> > On Thu, 29 Apr 2021 16:10:16 -0700
> > Joel Nider <joel@nider.org> wrote:

> >> -  \item[VIRTIO_F_RING_EVENT_IDX(29)] This feature enables the \field{used_event}
> >> +  \item[VIRTIO_F_EVENT_IDX(29)] This feature enables the \field{used_event}  
> > Hm. The VIRTIO_F_RING_ version actually matches well with
> > VIRTIO_F_RING_INDIRECT_DESC and VIRTIO_F_RING_PACKED. While the latter
> > is used consistently throughout the spec, we seem to use
> > VIRTIO_F_INDIRECT_DESC in other places. For added variety, Linux and
> > QEMU use VIRTIO_RING_F_INDIRECT_DESC and VIRTIO_RING_F_EVENT_IDX (but
> > VIRTIO_F_RING_PACKED.)  
> Clearly all of these flags apply to the v-rings - I don't think 
> including 'RING' to makes it any clearer. So in the interest of 
> readability, I would opt for the shorter flag names (more likely to fit 
> in a 80-char line). Linux (and the other OSes and hypervisors) will 
> eventually fall in line, once the spec is consistent.

Not so sure about implementations changing their terms, but I don't
think it's of much consequence.

> > We should be consistent within the spec, so I'd vote for using the
> > VIRTIO_F_RING_ versions everywhere here. (The Linux/QEMU variants are
> > still easily recognizable, so there's actually not much potential for
> > confusion.) The only downside is that this would mean more changes.  
> I fully support being consistent everywhere in the spec - that is my 
> primary concern. I noticed that over time, the flag name seems to be 
> gravitating towards the VIRTIO_F_EVENT_IDX (all places in section 2 
> already use this name), so that's why I just changed the last two places 
> that are not consistent. Truly, I will be happy once they are all the 
> same (one way or the other).

I have no strong preference for keeping the 'RING' particle, the main
issue is consistency. In any case, we should also clean up
INDIRECT_DESC.