Re: [Xen-devel] [PATCH] xen: add macro for defining variable length array in public headers

[Juergen Gross <jgross@xxxxxxxx>]

On 30.08.19 17:22, Jan Beulich wrote:
> On 30.08.2019 16:29, Juergen Gross wrote:
> > On 30.08.19 16:21, Jan Beulich wrote:
> > > On 30.08.2019 10:32, Juergen Gross wrote:
> > > > --- a/xen/include/public/xen.h
> > > > +++ b/xen/include/public/xen.h
> > > > @@ -53,6 +53,15 @@ DEFINE_XEN_GUEST_HANDLE(uint64_t);
> > > >    DEFINE_XEN_GUEST_HANDLE(xen_pfn_t);
> > > >    DEFINE_XEN_GUEST_HANDLE(xen_ulong_t);
> > > >    
> > > > +/* Define a variable length array (depends on compiler). */
> > > > +#if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L
> > > > +#define __XEN_VARLEN_ARRAY_SIZE
> > > > +#elif defined(__GNUC__)
> > > > +#define __XEN_VARLEN_ARRAY_SIZE  0
> > > > +#else
> > > > +#define __XEN_VARLEN_ARRAY_SIZE  1 /* variable size */
> > > > +#endif
> > > To be in line with the intentions, the C90 standard, and io/ring.h
> > > I'd suggest to use FLEX instead of VARLEN. Furthermore, especially
> > > in a public header, two double leading underscores need to go away.
> > >
> > > And then, with FLEX in the name, SIZE isn't really appropriate
> > > anymore. Therefore I see three possible names: XEN_FLEXIBLE_ARRAY,
> > > XEN_FLEX_ARRAY_DIMENSION (possibly just _DIM at its end), or
> > > XEN_FLEX_ARRAY_DESIGNATOR.
> > Okay to the "FLEX" part, but the "XEN_" prefix is not working due to
> > compat header generation (that will result in COMPAT_ prefix in the
> > compat headers).
> >
> > So any other ideas for a sensible prefix?
> Hmm, ugly. Perhaps all lower case then? Or have
xen_ and Xen_ are being converted, too.

> #define COMPAT_FLEX_... XEN_FLEX_...
>
> somewhere?
Seems as if doing that in include/public/xen-compat.h is working.


Juergen

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel