Re: [Xen-ia64-devel] [PATCH] xentrace buffer alignment

[Masaki Kanno <kanno.masaki@xxxxxxxxxxxxxx>]

Hi, Kevin

OK, I will send patch to the Xen-devel mailing list. 

Thanks,
 kan

>>-----Original Message-----
>>From: Masaki Kanno
>>Sent: 2005定11埖24晩 17:21
>>Hi, Rob, Kevin,
>>
>>> The alignment directive is necessary there since they're dynamically marked
>>> on an allocated buf. Or how about adding padding bytes to avoid using 
>>> compiler
>>> directive and ifdef? Then, still no need for "t_rec".
>>
>>Sorry, "t_rec" alignment is mistake. I thought "sizeof(t_rec) = 52 bytes".
>>
>>The patch was made on Kevin's idea.
>>However, I'm worried. When someone adds other members to "t_buf", isn't 
>>alignment
>>for ia64 forgotten?
>
>I meant to add padding bytes like "char padding[4]" with warning to developer 
>that 8 bytes alignment should be promised. 
But now I think your original ".align" approach may be easier without concern 
how many padding bytes need to be there on 
different architecture. So you can send out a patch with your original ".align" 
approach (but remove "ifdef __ia64__" to 
xen mailing list since it's a common code modification. Also please keep a 
comment to warn alignment requirement here. 
;-)
>
>Thanks,
>Kevin
>>
>>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 18:04:31 2005
>>@@ -69,6 +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.    */
>>+    unsigned int  align_buf; /* 8 bytes alignment for ia64                 */
>> };
>>
>> #endif /* __XEN_PUBLIC_TRACE_H__ */
>>
>>
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