Re: [Qemu-devel] [qemu-s390x] [PATCH v4] s390: diagnose 318 info reset and migration support

[Cornelia Huck <cohuck@redhat.com>]

On Tue, 14 May 2019 11:27:32 +0200
David Hildenbrand <david@redhat.com> wrote:

> On 14.05.19 11:25, Christian Borntraeger wrote:
> > 
> > 
> > On 14.05.19 11:23, Christian Borntraeger wrote:  
> >>
> >>
> >> On 14.05.19 11:20, David Hildenbrand wrote:  
> >>> On 14.05.19 11:10, Christian Borntraeger wrote:  
> >>>>
> >>>>
> >>>> On 14.05.19 10:59, David Hildenbrand wrote:  

> >>>>> We can
> >>>>>
> >>>>> 1. Fail to start with #cpus > 240 when diag318=on
> >>>>> 2. Remove the error once we support more than one SCLP response page
> >>>>>
> >>>>> Or
> >>>>>
> >>>>> 1. Allow to start with #cpus > 240 when diag318=on, but indicate only
> >>>>>    240 CPUs via SCLP
> >>>>> 2. Print a warning
> >>>>> 3. Remove the restriction and the warning once we support more than one
> >>>>>    SCLP response page
> >>>>>
> >>>>> While I prefer the second approach (similar to defining zPCI devices
> >>>>> without zpci=on), I could also live with the first approach.  
> >>>>
> >>>> I prefer approach 1.
> >>>>  
> >>>
> >>> Isn't approach #2 what we discussed (limiting sclp, but of course to 247
> >>> CPUs), but with an additional warning? I'm confused.  
> >>
> >> Different numbering interpretion. I was talking about 1 = "Allow to start with #cpus > 240 when diag318=on, but indicate only
> >> 240 CPUs via SCLP"  
> > 
> > So yes, variant 2 when I use your numbering. The only question is: do we need
> > a warning? It probably does not hurt.   
> 
> After all, we are talking about 1 VCPU that the guest can only use by
> indirect probing ... I leave that up to Collin :)

I'd prefer a warning... even if it is a corner case, I think it's
better to be explicit instead of silent.