Re: [PATCH v2 11/13] xen: remove GNUC check

[Peter Maydell]

On Thu, 26 Nov 2020 at 11:30, <marcandre.lureau@redhat.com> wrote:
>
> From: Marc-André Lureau <marcandre.lureau@redhat.com>
>
> QEMU requires Clang or GCC, that define and support __GNUC__ extensions
>
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  include/hw/xen/interface/io/ring.h | 9 ---------
>  1 file changed, 9 deletions(-)

>From QEMU's POV this change is good, but this header seems to have
originally been an import from the Xen public headers -- are we
happy to diverge from that original or do we prefer to stay as
close as possible to the upstream header? Cc'ing the Xen maintainers
for their opinion.

> diff --git a/include/hw/xen/interface/io/ring.h 
> b/include/hw/xen/interface/io/ring.h
> index 5d048b335c..115705f3f4 100644
> --- a/include/hw/xen/interface/io/ring.h
> +++ b/include/hw/xen/interface/io/ring.h
> @@ -206,21 +206,12 @@ typedef struct __name##_back_ring __name##_back_ring_t
>  #define RING_HAS_UNCONSUMED_RESPONSES(_r)                               \
>      ((_r)->sring->rsp_prod - (_r)->rsp_cons)
>
> -#ifdef __GNUC__
>  #define RING_HAS_UNCONSUMED_REQUESTS(_r) ({                             \
>      unsigned int req = (_r)->sring->req_prod - (_r)->req_cons;          \
>      unsigned int rsp = RING_SIZE(_r) -                                  \
>          ((_r)->req_cons - (_r)->rsp_prod_pvt);                          \
>      req < rsp ? req : rsp;                                              \
>  })
> -#else
> -/* Same as above, but without the nice GCC ({ ... }) syntax. */
> -#define RING_HAS_UNCONSUMED_REQUESTS(_r)                                \
> -    ((((_r)->sring->req_prod - (_r)->req_cons) <                        \
> -      (RING_SIZE(_r) - ((_r)->req_cons - (_r)->rsp_prod_pvt))) ?        \
> -     ((_r)->sring->req_prod - (_r)->req_cons) :                         \
> -     (RING_SIZE(_r) - ((_r)->req_cons - (_r)->rsp_prod_pvt)))
> -#endif
>
>  /* Direct access to individual ring elements, by index. */
>  #define RING_GET_REQUEST(_r, _idx)                                      \
> --


thanks
-- PMM