Re: [Qemu-devel] [PATCH 1/7] Add new macro QEMU_PACKED for packed C structures

[Andreas Färber]

Am 28.08.2011 um 22:43 schrieb Stefan Weil:

> A packed struct needs different gcc attributes for compilations
> with MinGW compilers because glib-2.0 adds compiler flag
> -mms-bitfields which modifies the packing algorithm.

Is that algorithm actually needed anywhere? If not, is there no GCC  
option to fix this centrally in configure for win32 only?

Andreas

> Attribute gcc_struct reverses the negative effects of -mms-bitfields.
> QEMU_PACKED sets this attribute and must be used for any packed
> struct which is affected by -mms-bitfields.
>
> Signed-off-by: Stefan Weil <address@hidden>
> ---
> compiler.h |    6 ++++++
> 1 files changed, 6 insertions(+), 0 deletions(-)
>
> diff --git a/compiler.h b/compiler.h
> index 9af5dc6..a2d5959 100644
> --- a/compiler.h
> +++ b/compiler.h
> @@ -12,6 +12,12 @@
> #define QEMU_WARN_UNUSED_RESULT
> #endif
>
> +#if defined(_WIN32)
> +# define QEMU_PACKED __attribute__((gcc_struct, packed))
> +#else
> +# define QEMU_PACKED __attribute__((packed))
> +#endif
> +
> #define QEMU_BUILD_BUG_ON(x) \
>     typedef char qemu_build_bug_on__##__LINE__[(x)?-1:1];
>
> --
> 1.7.0.4