Re: kernel unaligned accesses on IA64 in IDE

[Borislav Petkov <petkovbb@googlemail.com>]

On Fri, Aug 22, 2008 at 01:36:06PM -0700, Luck, Tony wrote:
> > How about long instead of int.  int leaves us with the possibility that
> > something else will expect 8 byte alignment.
> 
> How about this?
> 
> Align __cmd to ward off kernel unaligned access consoles messages on
> ia64 (and perhaps make an almost imperceptible performance improvement
> on other architectures that can handle unaligned access, but do so
> more slowly than aligned accesses).

That's probably the best solution for now. Testing...

> Signed-off-by: Tony Luck <tony.luck@intel.com>
> 
> ---
> 
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index e61f22b..a493a4b 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -211,7 +211,7 @@ struct request {
>  	 * when request is used as a packet command carrier
>  	 */
>  	unsigned short cmd_len;
> -	unsigned char __cmd[BLK_MAX_CDB];
> +	unsigned char __cmd[BLK_MAX_CDB] __attribute__((aligned(8)));
>  	unsigned char *cmd;
>  
>  	unsigned int data_len;

-- 
Regards/Gruss,
    Boris.