Re: [Qemu-devel] [PATCH v6 02/14] provide support for default implementations using weak symbols

[Blue Swirl]

On Thu, Aug 25, 2011 at 3:51 PM, Lluís <address@hidden> wrote:
> Routines using the QEMU_WEAK attribute can have a default implementation that
> can be later overriden just by re-implementing it.

Nack: weak attributes are only available for ELF and a.out.

> Signed-off-by: Lluís Vilanova <address@hidden>
> ---
>  compiler.h |   13 ++++++++++++-
>  1 files changed, 12 insertions(+), 1 deletions(-)
>
> diff --git a/compiler.h b/compiler.h
> index 9af5dc6..bc06760 100644
> --- a/compiler.h
> +++ b/compiler.h
> @@ -12,7 +12,7 @@
>  #define QEMU_WARN_UNUSED_RESULT
>  #endif
>
> -#define QEMU_BUILD_BUG_ON(x) \
> +#define QEMU_BUILD_BUG_ON(x)                                    \
>     typedef char qemu_build_bug_on__##__LINE__[(x)?-1:1];
>
>  #if defined __GNUC__
> @@ -31,4 +31,15 @@
>  #define GCC_FMT_ATTR(n, m)
>  #endif
>
> +/* Routine attribute to provide default (overridable) implementations.
> + *
> + * The code providing the default implementation must define 
> QEMU_WEAK_DEFAULT
> + * before including this file.
> + */
> +#if !defined(QEMU_WEAK_DEFAULT)
> +#define QEMU_WEAK
> +#else
> +#define QEMU_WEAK __attribute__((weak))
> +#endif
> +
>  #endif /* COMPILER_H */
>
>
>