Re: [Xen-devel] [PATCH] xentrace buffer alignment

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

I've already replied on the ia64-devel list. I'd like to know more 
about why explicit alignment is required.
 -- Keir

On 24 Nov 2005, at 12:06, Masaki Kanno wrote:

> Hi,
>
> I'm working to xentrace execution on ia64 now.
>
> When the "tbuf_size=" option was added,
> Xen cannot be booted and show the following messages.
>
> (XEN) About to call init_trace_bufs()
> (XEN) Xen trace buffers: initialised
> (XEN) About to call schedulers_start dom0=f0000000040ec100, 
> idle0_dom=f0000000040d2e10
> (XEN) ia64_handle_reflection: reflecting with priv=0!!
>
> Unaligned Reference fault occurred in trace function.
> This patch correct alignment of the trace buffer.
>
> Signed-off-by: Masaki Kanno <kanno.masaki@xxxxxxxxxxxxxx>
>
> Thanks,
>  kan
>
> diff -r 51f32d60536b xen/include/public/trace.h
> --- a/xen/include/public/trace.h        Fri Nov 18 00:35:14 2005
> +++ b/xen/include/public/trace.h        Thu Nov 24 20:49:02 2005
> @@ -69,7 +69,7 @@
>      unsigned int  prod;      /* Next item to be produced by Xen.      
>      */
>      unsigned int  nr_recs;   /* Number of records in this trace 
> buffer.    */
>      /* 'nr_recs' records follow immediately after the meta-data 
> header.    */
> -};
> +} __attribute__((__aligned__(8))); /* 8 bytes alignment for ia64      
>      */
>  #endif /* __XEN_PUBLIC_TRACE_H__ */
>
>
>
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