Re: [PATCH v2 2/7] Documentation: s390-diag.rst: make diag500 a generic KVM hypercall

[David Hildenbrand]

On 15.10.24 10:46, Heiko Carstens wrote:
> On Tue, Oct 15, 2024 at 10:32:43AM +0200, David Hildenbrand wrote:
> > On 15.10.24 10:21, Heiko Carstens wrote:
> > > On Tue, Oct 15, 2024 at 10:16:20AM +0200, David Hildenbrand wrote:
> > > > On 15.10.24 10:12, Heiko Carstens wrote:
> > > > > On Mon, Oct 14, 2024 at 09:35:27PM +0200, David Hildenbrand wrote:
> > > > > > On 14.10.24 20:04, Heiko Carstens wrote:
> > > > > "If only there would be a query subcode available, so that the program
> > > > > check handling would not be necessary; but in particular my new subcode
> > > > > is not worth adding it" :)
> > > > >
> > > > > Anyway, I do not care too much.
> > > >
> > > > Okay, I see your point: it would allow for removing the program check
> > > > handling from the STORAGE LIMIT invocation.
> > > >
> > > > ... if only we wouldn't need the exact same program check handling for the
> > > > new query subfunction :P
> > >
> > > Yeah yeah, but I think you got that this might help in the future.
> >
> > Right. Adding it later also doesn't quite help to get rid of the checks
> > here, because some user space might implement STORAGE LIMIT without QUERY.
>
> This would only help if the diag500 documentation would state that
> implementation of the QUERY subcode is mandatory. That is: for every
> new subcode larger than the QUERY subcode QUERY must also exist.
>
> That way we only would have to implement program check handling once,
> if a program check happens on QUERY none of the newer subcodes is
> available, otherwise the return value would indicate that.
>
> Otherwise this whole excercise would be pointless.

Yes, that would be the idea.

--
Cheers,

David / dhildenb