On Tue, 11 May 2021 17:38:04 +0200
David Hildenbrand <david@xxxxxxxxxx> wrote:
> On 11.05.21 16:41, Claudio Imbrenda wrote:
> > 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
>
> IMHO checking with a mask here multiple facilities will be very error
> prone either way ... and we only have a single byte to check for.
as I said, I do not have a strong opinion either way :)
