Re: [Qemu-devel] [RFC 06/28] s390x/cpumodel: introduce CPU feature group definitions

[Eduardo Habkost]

On Wed, Jun 22, 2016 at 08:19:44AM +0200, David Hildenbrand wrote:
> > On 22.06.2016 15:02, David Hildenbrand wrote:
> > > Let's use the generated groups to create feature group representations for
> > > the user. These groups can later be used to enable/disable multiple
> > > features in one shot and will be used to reduce the amount of reported
> > > features to the user if all subfeatures are in place.
> > > 
> > > Acked-by: Cornelia Huck <address@hidden>
> > > Signed-off-by: David Hildenbrand <address@hidden>
> > > ---
> > >  target-s390x/cpu_features.c | 44 
> > > +++++++++++++++++++++++++++++++++++++++++++-
> > >  target-s390x/cpu_features.h | 23 +++++++++++++++++++++++
> > >  2 files changed, 66 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/target-s390x/cpu_features.c b/target-s390x/cpu_features.c
> > > index c78a189..6ec2bfc 100644
> > > --- a/target-s390x/cpu_features.c
> > > +++ b/target-s390x/cpu_features.c
> > > @@ -12,6 +12,7 @@
> > >  
> > >  #include "qemu/osdep.h"
> > >  #include "cpu_features.h"
> > > +#include "gen-features.h"
> > >  
> > >  #define FEAT_INIT(_name, _type, _bit, _desc) \
> > >      {                                                \
> > > @@ -321,14 +322,55 @@ void s390_add_from_feat_block(S390FeatBitmap 
> > > features, S390FeatType type,
> > >      }
> > >  }
> > >  
> > > -void s390_feat_bitmap_to_ascii(const S390FeatBitmap bitmap, void *opaque,
> > > +void s390_feat_bitmap_to_ascii(const S390FeatBitmap features, void 
> > > *opaque,
> > >                                 void (*fn)(const char *name, void 
> > > *opaque))
> > >  {
> > > +    S390FeatBitmap bitmap, tmp;
> > > +    S390FeatGroup group;
> > >      S390Feat feat;
> > >  
> > > +    bitmap_copy(bitmap, features, S390_FEAT_MAX);
> > > +
> > > +    /* process whole groups first */
> > > +    for (group = 0; group < S390_FEAT_GROUP_MAX; group++) {
> > > +        const S390FeatGroupDef *def = s390_feat_group_def(group);
> > > +
> > > +        bitmap_and(tmp, bitmap, def->feat, S390_FEAT_MAX);
> > > +        if (bitmap_equal(tmp, def->feat, S390_FEAT_MAX)) {
> > > +            bitmap_andnot(bitmap, bitmap, def->feat, S390_FEAT_MAX);
> > > +            (*fn)(def->name, opaque);  
> > 
> > Maybe simply write
> >                fn(dev->name, opaque);
> > instead?
> 
> Will that work? As fn is a pointer I am not a 100% sure. If so, I'll change 
> it!

Both are 100% equivalent. Actually, the expression denoting the
function to be called has to be a function pointer, but (*fn)
happens to be magically converted back to a function pointer
because the spec says so.

-- 
Eduardo