Re: [Xen-ia64-devel] [PATCH] xentrace buffer alignment - Masaki Kanno - com.xensource.lists.xen-ia64-devel

13 messages in com.xensource.lists.xen-ia64-develRe: [Xen-ia64-devel] [PATCH] xentrace...

From	Sent On	Attachments
Masaki Kanno	23 Nov 2005 20:35
Rob Gardner	23 Nov 2005 20:49
Tian, Kevin	23 Nov 2005 21:17
Tian, Kevin	23 Nov 2005 21:50
Tian, Kevin	23 Nov 2005 21:58
Masaki Kanno	24 Nov 2005 01:20
Tian, Kevin	24 Nov 2005 02:10
Masaki Kanno	24 Nov 2005 04:05
Keir Fraser	24 Nov 2005 05:33
Tian, Kevin	24 Nov 2005 05:51
Tian, Kevin	24 Nov 2005 05:54
Tian, Kevin	24 Nov 2005 06:07
Keir Fraser	24 Nov 2005 06:11

Subject:	Re: [Xen-ia64-devel] [PATCH] xentrace buffer alignment
From:	Masaki Kanno (kann...@jp.fujitsu.com)
Date:	11/24/2005 04:05:15 AM
List:	com.xensource.lists.xen-ia64-devel

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 <kann...@jp.fujitsu.com>

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__ */