[dpdk-dev] [PATCH 1/3] evendev: fix inconsistency in event queue config

[Van Haaren, Harry]

> From: Pavan Nikhilesh Bhagavatula [mailto:pbhagavatula at caviumnetworks.com]
> Sent: Monday, October 23, 2017 9:42 AM
> To: Van Haaren, Harry <harry.van.haaren at intel.com>;
> jerin.jacob at caviumnetworks.com
> Cc: dev at dpdk.org
> Subject: Re: [dpdk-dev] [PATCH 1/3] evendev: fix inconsistency in event
> queue config
> 
> On Mon, Oct 23, 2017 at 08:04:26AM +0000, Van Haaren, Harry wrote:
> > > From: Pavan Nikhilesh Bhagavatula
> [mailto:pbhagavatula at caviumnetworks.com]
> > > Sent: Friday, October 20, 2017 8:09 PM
> > > To: Van Haaren, Harry <harry.van.haaren at intel.com>
> > > Cc: dev at dpdk.org
> > > Subject: Re: [dpdk-dev] [PATCH 1/3] evendev: fix inconsistency in event
> > > queue config
> > >
> > > On Fri, Oct 20, 2017 at 04:38:57PM +0000, Van Haaren, Harry wrote:
> >
> > <big snip>
> >
> > > > Sure, I see two sane-ish options:
> > > >
> > > > 1) Return an error code from get_attr(), which actually means "ALL
> TYPES".
> > > Feels a bit weird, because an error value is really a valid return.
> > > >
> > > > 2) Return UINT_MAX (aka, -1) as the scheduling value. Applications
> that
> > > use/care about the scheduling type must check, others can ignore it.
> > > >
> > > > I'm not sure which of these is the better/less-bad solution. Opinions?
> -H
> > > >
> > >
> > > I think 1st option would be good, we could use ENOTUNIQ to represent
> that
> > > the
> > > queue type is "ALL TYPE".
> > >
> > > Thoughts?
> >
> >
> > OK with me!
> >
> Hey Harry/Jerin,
> 
> Sadly ENOTUNIQ is not supported on freebsd so, would returning EOPNOTSUPP
> make
> sense as it is closest error message that has similar meaning.
> I found ENOATTR in freebsd but that's not supported on linux.


EOVERFLOW seems to be supported on both, and suggests that the ALL_TYPES return would "overflow", aka is too big, aka, too many types to return?

Documenting the return is IMO more important that exactly what the value is - given there's no logical errno to use, lets use this and document it clearly so when somebody looks at the docs, they'll gain the correct undersanding?

-H