Re: [Qemu-devel] [kvm-unit-tests PATCH v5 08/11] libcflat: add IS_ALIGNED() macro, and page sizes

[Andrew Jones]

On Fri, Nov 11, 2016 at 03:02:42PM +0000, Alex Bennée wrote:
> 
> Andrew Jones <address@hidden> writes:
> 
> > From: Peter Xu <address@hidden>
> >
> > These macros will be useful to do page alignment checks.
> >
> > Reviewed-by: Andre Przywara <address@hidden>
> > Signed-off-by: Peter Xu <address@hidden>
> > [drew: also added SZ_64K]
> > Signed-off-by: Andrew Jones <address@hidden>
> > ---
> >  lib/libcflat.h | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/lib/libcflat.h b/lib/libcflat.h
> > index 82005f5d014f..143fc53061fe 100644
> > --- a/lib/libcflat.h
> > +++ b/lib/libcflat.h
> > @@ -33,6 +33,12 @@
> >  #define __ALIGN_MASK(x, mask)      (((x) + (mask)) & ~(mask))
> >  #define __ALIGN(x, a)              __ALIGN_MASK(x, (typeof(x))(a) - 1)
> >  #define ALIGN(x, a)                __ALIGN((x), (a))
> > +#define IS_ALIGNED(x, a)   (((x) & ((typeof(x))(a) - 1)) == 0)
> > +
> > +#define SZ_4K                      (0x1000)
> > +#define SZ_64K                     (0x10000)
> > +#define SZ_2M                      (0x200000)
> > +#define SZ_1G                      (0x40000000)
> 
> We don't seem to use IS_ALIGNED, or in fact anything apart from SZ_64K
> (which is multiplied by 2 anyway) so I'm not sure if this patch is worth
> it for this series.

I cherry-picked this patch (and modified it to add SZ_64K) from a
different series, one currently in-flight from Peter Xu.

> 
> Stylistically I thought (1 << foo) was preferred for setting of
> individual bits? Otherwise I'd be tempted to line the values up with
> zero padding to make it easier to read the bit position.

I agree with the style comments and will do that for v6.

> 
> >
> >  typedef uint8_t            u8;
> >  typedef int8_t             s8;
> 
>

Thanks,
drew