Re: [PATCH v2] xen/config.h: Move BITS_PER_* definitions from asm/config.h to xen/config.h

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

On 3/28/25 8:49 AM, Jan Beulich wrote:

> On 27.03.2025 18:33, Oleksii Kurochko wrote:
> > BITS_PER_* values can be defined in a common way using compiler-provided macros.
> > Thus, these definitions are moved to xen/config.h to reduce duplication across
> > architectures.
> >
> > Additionally, *_BYTEORDER macros are removed, as BITS_PER_* values now come
> > directly from the compiler environment.
> >
> > The arch_fls() implementation for Arm and PPC is updated to use BITS_PER_INT
> > instead of a hardcoded value of 32.
> >
> > Suggested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> > Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
> >       
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
> albeit ...
>
> > --- a/xen/include/xen/config.h
> > +++ b/xen/include/xen/config.h
> > @@ -98,4 +98,14 @@
> >  #define ZERO_BLOCK_PTR ((void *)-1L)
> >  #endif
> >  
> > +#define BYTES_PER_LONG  __SIZEOF_LONG__
> >       
> ... I remain unconvinced that we actually need this (yet then not its sibling
> for int). All uses I can spot could be replaced by sizeof(long). This (and its
> sibling) would be needed only for #if uses, and there I would then wonder why
> we couldn't use __SIZEOF_LONG__ directly, now that we assume its universally
> available.
>     
I left only because BYTES_PER_LONG is used in ARM and x86 code.
If no one minds, I can replace BYTES_PER_LONG with __SIZEOF_LONG__.

~ Oleksii