Re: [PATCH v3 1/4] Add VIRTIO_RING_F_INDIRECT_SIZE

[Cornelia Huck <cohuck@redhat.com>]

On Fri, Mar 18 2022, Christian Schoenebeck <qemu_oss@crudebyte.com> wrote:

> On Donnerstag, 17. MÃrz 2022 14:40:27 CET Cornelia Huck wrote:
>> On Wed, Mar 16 2022, Christian Schoenebeck <qemu_oss@crudebyte.com> wrote:
>> > This new feature flag allows to decouple the maximum amount of
>> > descriptors in indirect descriptor tables from the Queue Size.
>> > 
>> > The new term "Queue Indirect Size" is introduced for this purpose,
>> > which is a transport specific configuration whose negotiation is
>> > further specified for each transport with subsequent patches.
>> > 
>> > Fixes: https://github.com/oasis-tcs/virtio-spec/issues/122
>> > Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
>> > Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
>> > ---
>> > 
>> >  content.tex     | 32 ++++++++++++++++++++++++++++++--
>> >  packed-ring.tex |  2 +-
>> >  split-ring.tex  |  8 ++++++--
>> >  3 files changed, 37 insertions(+), 5 deletions(-)
>> > 
>> > diff --git a/content.tex b/content.tex
>> > index c6f116c..685525d 100644
>> > --- a/content.tex
>> > +++ b/content.tex
>> 
>> (...)
>> 
>> > @@ -1051,6 +1051,10 @@ \subsubsection{Common configuration structure
>> > layout}\label{sec:Virtio Transport> 
>> >  present either a value of 0 or a power of 2 in
>> >  \field{queue_size}.
>> > 
>> > +If VIRTIO_RING_F_INDIRECT_SIZE has been negotiated, the device MUST
>> > provide the +Queue Indirect Size supported by device, which is a
>> > transport specific
>> "supported by the device", or maybe "it supports"?
>
> Article "the" is missing here, yes. Both "the device" or "it" would be fine.

Yes; just use whichever you prefer :)

>
>> > +configuration. It MUST allow the driver to set a lower value.
>> 
>> Maybe "It MUST allow the driver to specify a lower maximum size." ?
>
> That exact phrase was actually suggested by you (2021-12-14 18:20). I have no 
> strong opinion on that. I find the existing "to set a lower value" clear 
> enough and a less complicated wording though.

Heh :) I do not really have a strong opinion here (hence the "maybe".)

>> I'm not sure whether we would actually need some normative statements in
>> the sections below, but probably not.
>
> Like what would you potentially miss here?

That we MUST also negotiate the value if we negotiate the feature. But
as I wrote, we probably don't need to be that explicit.