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Date: Sat, 17 Oct 2009 18:03:41 +0200
From: Frederic Weisbecker <fweisbec@gmail.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: LKML <linux-kernel@vger.kernel.org>, Peter Zijlstra <peterz@infradead.org>,
       Arnaldo Carvalho de Melo <acme@redhat.com>,
       Mike Galbraith <efault@gmx.de>, Paul Mackerras <paulus@samba.org>,
       Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH 3/2] perf tools: Use DECLARE_BITMAP instead of an
	open-coded array
Message-ID: <20091017160338.GA10344@nowhere>
References: <20091016074222.GD30019@elte.hu> <1255795038-13751-1-git-send-email-fweisbec@gmail.com>
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On Sat, Oct 17, 2009 at 05:57:18PM +0200, Frederic Weisbecker wrote:
> Use DECLARE_BITMAP instead of an open coded array for our bitmap
> of featured sections.
> 
> This makes the array an unsigned long instead of a u64 but since
> we use a 256 bits bitmap, the array size shouldn't vary between
> different boxes.


That said I would really feel more comfortable if someone can
confirm that.



> @@ -143,12 +141,12 @@ struct perf_file_header {
>  	struct perf_file_section	attrs;
>  	struct perf_file_section	data;
>  	struct perf_file_section	event_types;
> -	feat_mask_t			adds_features;
> +	DECLARE_BITMAP(adds_features, HEADER_FEAT_BITS);


I think having adds_features as an unsigned long won't
hurt because we have HEAD_FEAT_BITS % 64 == 0

It would certainly hurt if we had, say, HEAD_FEAT_BITS = 257

But may be I forget a corner case. I hope someone can double
check that. Thanks.