Re: [Xen-devel] [PATCH v9 04/11] public: xen.h: add definitions for UUID handling

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi Jan,

On 11/10/17 09:54, Jan Beulich wrote:
> > > > On 11.10.17 at 01:24, <sstabellini@xxxxxxxxxx> wrote:
> > On Tue, 10 Oct 2017, Volodymyr Babchuk wrote:
> > > --- a/xen/include/public/xen.h
> > > +++ b/xen/include/public/xen.h
> > > @@ -930,6 +930,39 @@ __DEFINE_XEN_GUEST_HANDLE(uint16, uint16_t);
> > >   __DEFINE_XEN_GUEST_HANDLE(uint32, uint32_t);
> > >   __DEFINE_XEN_GUEST_HANDLE(uint64, uint64_t);
> > >   
> > > +typedef struct {
> > > +    uint8_t a[16];
> > > +} xen_uuid_t;
> > > +
> > > +/*
> > > + * XEN_DEFINE_UUID(0x00112233, 0x4455, 0x6677, 0x8899,
> > > + *                 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff)
> > > + * will construct UUID 00112233-4455-6677-8899-aabbccddeeff presented as
> > > + * {0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88,
> > > + * 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff};
> > > + *
> > > + * NB: This is compatible with Linux kernel and with libuuid, but it is not
> > > + * compatible with Microsoft, as they use mixed-endian encoding (some
> > > + * components are little-endian, some are big-endian).
> > > + */
> > > +#define XEN_DEFINE_UUID_(a, b, c, d, e1, e2, e3, e4, e5, e6)            \
> > > +    {{((a) >> 24) & 0xFF, ((a) >> 16) & 0xFF,                           \
> > > +      ((a) >>  8) & 0xFF, ((a) >>  0) & 0xFF,                           \
> > > +      ((b) >>  8) & 0xFF, ((b) >>  0) & 0xFF,                           \
> > > +      ((c) >>  8) & 0xFF, ((c) >>  0) & 0xFF,                           \
> > > +      ((d) >>  8) & 0xFF, ((d) >>  0) & 0xFF,                           \
> > > +                e1, e2, e3, e4, e5, e6}}
> > > +
> > > +/* Compound literals are supported in C99 and later. */
> > > +#if defined (__STDC_VERSION__) && __STDC_VERSION__ >= 199901L
> > > +#define XEN_DEFINE_UUID(a, b, c, d, e1, e2, e3, e4, e5, e6)             \
> > > +    ((xen_uuid_t)XEN_DEFINE_UUID_(a, b, c, d, e1, e2, e3, e4, e5, e6))
> > > +#else
> > > +#define XEN_DEFINE_UUID(a, b, c, d, e1, e2, e3, e4, e5, e6)             \
> > > +    XEN_DEFINE_UUID_(a, b, c, d, e1, e2, e3, e4, e5, e6)
> > > +
> > > +#endif /* defined (__STDC_VERSION__) && __STDC_VERSION__ >= 199901L */
> > > +
> > >   #endif /* !__ASSEMBLY__ */
> > >   
> > >   /* Default definitions for macros used by domctl/sysctl. */
> > This looks good to me, but I would like to get Jan's opinion on this.
> > Ideally we would commit the series tomorrow before the code freeze.
> While I can live with it being the way it is now, I've already
> indicated that I'd prefer __GNUC__ to also be checked for
> here. As that's a relaxation, it wouldn't be a problem to add
> later, I think (but I can't exclude I'm overlooking something,
> so it would feel better if it was done the intended final way
> from the beginning).
To be clear, you ask to do:

#if defined(__GNUC__) || (defined(__STDC_VERSION__) && __STDC_VERSION__ 
>= 199901L)
am I correct?

Cheers,

--
Julien Grall

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