Re: [Qemu-devel] [qemu-s390x] [PATCH 1/1] 390x/cpumodel: document S390FeatDef.bit not applicable

[Cornelia Huck <cohuck@redhat.com>]

On Tue, 20 Feb 2018 17:04:19 +0100
Christian Borntraeger <borntraeger@de.ibm.com> wrote:

> On 02/20/2018 04:55 PM, David Hildenbrand wrote:
> > On 20.02.2018 16:53, Cornelia Huck wrote:  
> >> On Tue, 20 Feb 2018 16:07:13 +0100
> >> Halil Pasic <pasic@linux.vnet.ibm.com> wrote:
> >>  
> >>> The 'bit' field of the 'S390FeatDef' structure is not applicable to all
> >>> it's instances. Currently a this field is not applicable, and remains  
> >>
> >> s/it's/its/
> >>
> >> s/a this/this/
> >>  
> >>> unused, iff the feature is of type S390_FEAT_TYPE_MISC. Having the value 0
> >>> specified for multiple such feature definition  was a little confusing,
> >>> as it's a perfectly legit bit value, and as usually the value of the bit
> >>> field is ought to be unique for each feature.
> >>>
> >>> Let's document this, and hopefully reduce the potential for confusion.
> >>>
> >>> Signed-off-by: Halil Pasic <pasic@linux.vnet.ibm.com>
> >>> ---
> >>>
> >>> Hi!
> >>>
> >>> This may be an overkill. A comment where the misc features
> >>> are defined would do to, but I think this is nicer. So
> >>> I decided to try it with this approach first.  
> >>
> >> Is there likely to be anything else than FEAT_MISC _not_ using .bit? If
> >> not, would it be better to at a comment to the FEAT_MISC definition?  
> > 
> > Doubt it right now. I would sign the "overkill" part :)  
> 
> I can cconfirm that this code caused some questions and it took me some
> minutes to remember why 0 and 0 was ok. So I certainly want to have a comment
> of some form.
> 

I'd prefer a comment about FEAT_MISC usage rather than a magic value.