Re: [kvm-unit-tests PATCH v2 2/5] s390x: sclp: Remove unnecessary padding from struct sclp_facilities

["Nico Boehr" <nrb@linux.ibm.com>]

On Tue Mar 24, 2026 at 4:28 PM CET, Christoph Schlameuss wrote:
> Struct sclp_facilities is only used within the guest to keep the facility
> information. Nothing bad should happen when the struct size changes in the
> future.
>
> Suggested-by: Janosch Frank <frankja@linux.ibm.com>
> Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
> ---
>  lib/s390x/sclp.h | 1 -
>  1 file changed, 1 deletion(-)
>
> diff --git a/lib/s390x/sclp.h b/lib/s390x/sclp.h
> index 22f120d1b7ea7d1c3fe822385d0c689e5b3459fe..42a2f2e9f25a45d3ebd71729df0d9d6d93a4fb50 100644
> --- a/lib/s390x/sclp.h
> +++ b/lib/s390x/sclp.h
> @@ -132,7 +132,6 @@ struct sclp_facilities {
>  	uint64_t has_kss : 1;
>  	uint64_t has_pfmfi : 1;
>  	uint64_t has_ibs : 1;
> -	uint64_t : 64 - 15;
>  };

If I'm not mistaken this is already wrong if I did proper counting since
there are 17 bits and we only subtract 15.

Since bit fields are guaranteed to be allocated left to right (see [1], p 14),
this change makes sense.

Reviewed-by: Nico Boehr <nrb@linux.ibm.com>

[1] ELF Application Binary Interface s390x Supplement, Version 1.6