Re: [Xen-devel] [PATCH v10] xen: add para-virtual sound interface header file

[Oleksandr Andrushchenko <andr2000@xxxxxxxxx>]

On 11/25/2016 09:11 AM, Jan Beulich wrote:
> > > > On 24.11.16 at 18:11, <andr2000@xxxxxxxxx> wrote:
> > > > +struct xensnd_close_req {
> > > > +};
> > > I'm afraid structures without any members aren't permitted by C89.
> > There are 2 options I see:
> > 1. Remove empty structures
> > 2. Leave them in, but add a comment and add a dummy place holder
> > I would prefer option 1 as this way the interface seems to be clearer,
> > like all requests are defined etc.
> I'm not really sure which option is better, so I'd leave this to the
> (soon to be sole) maintainer of those files (Konrad - I don't think
> I've seen v2 of that patch yet).
I am preparing a new patch now, will publish soon
> > > > +struct xensnd_request {
> > > > +     uint8_t raw[64];
> > > > +};
> > > > +
> > > > +struct xensnd_response {
> > > > +     uint8_t raw[64];
> > > > +};
> > > What are these two needed for now? If you want to enforce a
> > > minimum size, that would better go ...
> > That is because we want to be cache line aligned. What it means in practice
> > is not clear as we have so many HW around, so it is not possible to
> > fit all. So the options could be:
> > 1. 32 or 64
> > 2. 48 I think is not an option here
> > I would stick to 32
> I don't understand why you switched over to discussing size, when all
> I've asked for is to change the placement of these size enforcing
> constructs (after all by themselves they're not useful types).
You are absolutely right, will fix
> Jan

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