On Tue, 11 May 2021 13:43:36 +0200
David Hildenbrand <david@xxxxxxxxxx> wrote:
> On 10.05.21 17:00, Janosch Frank wrote:
> > Lets grab more of the feature bits from SCLP read info so we can use
> > them in the cpumodel tests.
> >
> > Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
> > Reviewed-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
> > ---
> > lib/s390x/sclp.c | 20 ++++++++++++++++++++
> > lib/s390x/sclp.h | 38 +++++++++++++++++++++++++++++++++++---
> > 2 files changed, 55 insertions(+), 3 deletions(-)
> >
> > diff --git a/lib/s390x/sclp.c b/lib/s390x/sclp.c
> > index f11c2035..f25cfdb2 100644
> > --- a/lib/s390x/sclp.c
> > +++ b/lib/s390x/sclp.c
> > @@ -129,6 +129,13 @@ CPUEntry *sclp_get_cpu_entries(void)
> > return (CPUEntry *)(_read_info + read_info->offset_cpu);
> > }
> >
> > +static bool sclp_feat_check(int byte, int mask)
> > +{
> > + uint8_t *rib = (uint8_t *)read_info;
> > +
> > + return !!(rib[byte] & mask);
> > +}
>
> Instead of a mask, I'd just check for bit (offset) numbers within the
> byte.
>
> static bool sclp_feat_check(int byte, int bit)
> {
> uint8_t *rib = (uint8_t *)read_info;
>
> return !!(rib[byte] & (0x80 >> bit));
> }
using a mask might be useful to check multiple facilities at the same
time, but in that case the check should be
return (rib[byte] & mask) == mask
I have no strong opinions either way
