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Date:   Thu, 12 Nov 2020 12:57:10 +0100
From:   Jiri Olsa <jolsa@redhat.com>
To:     Andi Kleen <ak@linux.intel.com>
Cc:     Jiri Olsa <jolsa@kernel.org>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        lkml <linux-kernel@vger.kernel.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Ingo Molnar <mingo@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Michael Petlan <mpetlan@redhat.com>,
        Song Liu <songliubraving@fb.com>,
        Ian Rogers <irogers@google.com>,
        Stephane Eranian <eranian@google.com>,
        Alexey Budankov <alexey.budankov@linux.intel.com>,
        Adrian Hunter <adrian.hunter@intel.com>
Subject: Re: [PATCH 24/24] perf record: Add --buildid-mmap option to enable
 mmap's build id
Message-ID: <20201112115710.GE619201@krava>
References: <20201109215415.400153-1-jolsa@kernel.org>
 <20201109215415.400153-25-jolsa@kernel.org>
 <20201111170046.GB466880@tassilo.jf.intel.com>
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On Wed, Nov 11, 2020 at 09:00:46AM -0800, Andi Kleen wrote:
> On Mon, Nov 09, 2020 at 10:54:15PM +0100, Jiri Olsa wrote:
> > Adding --buildid-mmap option to enable build id in mmap2 events.
> > It will only work if there's kernel support for that and it disables
> > build id cache (implies --no-buildid).
> 
> What's the point of the option? Why not enable it by default
> if the kernel supports it?
> 
> With the option most user won't get the benefit.
> 
> The only reason I can think of for an option would be to disable
> so that old tools can still process.

yes, that was request in the rfc post, we want the new default
perf.data be still readable by older perf tools

jirka