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Message-ID: <52A9BE15.4090105@intel.com>
Date: Thu, 12 Dec 2013 15:45:57 +0200
From: Adrian Hunter <adrian.hunter@intel.com>
Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki,
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To: Andi Kleen <ak@linux.intel.com>
CC: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
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        David Ahern <dsahern@gmail.com>,
        Frederic Weisbecker <fweisbec@gmail.com>, Jiri Olsa <jolsa@redhat.com>,
        Mike Galbraith <efault@gmx.de>, Namhyung Kim <namhyung@gmail.com>,
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        Stephane Eranian <eranian@google.com>
Subject: Re: [PATCH v0 21/71] perf tools: Add feature test for __sync_val_compare_and_swap
References: <1386765443-26966-1-git-send-email-alexander.shishkin@linux.intel.com> <1386765443-26966-22-git-send-email-alexander.shishkin@linux.intel.com> <20131211192407.GD1458@ghostprotocols.net> <20131211200721.GN22695@tassilo.jf.intel.com>
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On 11/12/13 22:07, Andi Kleen wrote:
>> Can you provide more info about these gcc builtins and what is the
>> minimum system where this test will succeed?
> 
> CMPXCHG for x86 is available since the 486 or so, so practically
> everywhere.
> 
> I think that's mainly for other architectures.
> 
> it would be reasonable to just use #if defined(__x86_64__) || defined(__i386__)
> instead.

__sync_val_compare_and_swap() is being used in the itrace abstraction which
is architecture neutral, so I can't use x86 defines.