Re: [Qemu-devel] [PATCH] virtio-input: const_le16 and const_le32 not build time constant

[Alexander Graf <agraf@suse.de>]

On 01.06.15 15:51, Michael Mueller wrote:
> As the implementation of const_le16 and const_le32 is not build time constant
> on big endian systems this need to be fixed.
> 
>   CC    hw/input/virtio-input-hid.o
> hw/input/virtio-input-hid.c:340:13: error: initializer element is not constant
> hw/input/virtio-input-hid.c:340:13: error: (near initialization for ‘virtio_keyboard_config[1].u.ids.bustype’)
> ...
> 
> Signed-off-by: Michael Mueller <mimu@linux.vnet.ibm.com>

Thanks a lot for this patch. It fixes current compile breakage on
upstream QEMU for me - or on any big endian system for that matter.

For the time being I've included it into my ppc-next tree, but I'd
prefer if this gets merged directly before I flush it (for
bisectability's sake).


Alex

> ---
>  include/hw/virtio/virtio-input.h | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/include/hw/virtio/virtio-input.h b/include/hw/virtio/virtio-input.h
> index a265519..bcee355 100644
> --- a/include/hw/virtio/virtio-input.h
> +++ b/include/hw/virtio/virtio-input.h
> @@ -14,8 +14,14 @@ typedef struct virtio_input_config virtio_input_config;
>  typedef struct virtio_input_event virtio_input_event;
>  
>  #if defined(HOST_WORDS_BIGENDIAN)
> -# define const_le32(_x) bswap32(_x)
> -# define const_le16(_x) bswap32(_x)
> +# define const_le32(_x)                          \
> +    (((_x & 0x000000ffU) << 24) |                \
> +     ((_x & 0x0000ff00U) <<  8) |                \
> +     ((_x & 0x00ff0000U) >>  8) |                \
> +     ((_x & 0xff000000U) >> 24))
> +# define const_le16(_x)                          \
> +    (((_x & 0x00ff) << 8) |                      \
> +     ((_x & 0xff00) >> 8))
>  #else
>  # define const_le32(_x) (_x)
>  # define const_le16(_x) (_x)
>