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Date:   Wed, 1 Sep 2021 13:25:37 -0300
From:   Arnaldo Carvalho de Melo <acme@kernel.org>
To:     Leo Yan <leo.yan@linaro.org>
Cc:     James Clark <james.clark@arm.com>, mathieu.poirier@linaro.org,
        coresight@lists.linaro.org, linux-perf-users@vger.kernel.org,
        mike.leach@linaro.org, suzuki.poulose@arm.com,
        John Garry <john.garry@huawei.com>,
        Will Deacon <will@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@redhat.com>,
        Namhyung Kim <namhyung@kernel.org>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 9/9] perf cs-etm: Show a warning for an unknown magic
 number
Message-ID: <YS+pgZMpFmnRlMuT@kernel.org>
References: <20210806134109.1182235-1-james.clark@arm.com>
 <20210806134109.1182235-10-james.clark@arm.com>
 <20210824083615.GF204566@leoy-ThinkPad-X240s>
 <YS+iOrcPTzQfmbqU@kernel.org>
 <YS+lTXyuC+9VTrxd@kernel.org>
 <YS+neCZler56Hs2D@kernel.org>
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Em Wed, Sep 01, 2021 at 01:16:56PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Wed, Sep 01, 2021 at 01:07:41PM -0300, Arnaldo Carvalho de Melo escreveu:
> > Em Wed, Sep 01, 2021 at 12:54:34PM -0300, Arnaldo Carvalho de Melo escreveu:
> > > Em Tue, Aug 24, 2021 at 04:36:15PM +0800, Leo Yan escreveu:
> > > > On Fri, Aug 06, 2021 at 02:41:09PM +0100, James Clark wrote:
> > > > > Currently perf reports "Cannot allocate memory" which isn't very helpful
> > > > > for a potentially user facing issue. If we add a new magic number in
> > > > > the future, perf will be able to report unrecognised magic numbers.
> > > > > 
> > > > > Signed-off-by: James Clark <james.clark@arm.com>
> > > > 
> > > > Reviewed-by: Leo Yan <leo.yan@linaro.org>
> > > 
> > > Applies cleanly to my tree, test building it now, holler if there is
> > > something that prevents it from being merged.
> > 
> > I´m now trying to fix this up, I applied it using 'b4', so no patch
> > should have gone missing...
> 
> So its probably related to:
> 
> ⬢[acme@toolbox perf]$ rpm -qa | grep opencsd
> opencsd-1.0.0-1.fc34.x86_64
> opencsd-devel-1.0.0-1.fc34.x86_64
> ⬢[acme@toolbox perf]$
> 
> In which case the usual mechanism is to test if we have what is needed
> via tools/build/feature/test-_____.c, lemme check...

There is a test and it fails, of course:

⬢[acme@toolbox perf]$ cat /tmp/build/perf/feature/test-libopencsd.make.output
test-libopencsd.c:9:2: error: #error "OpenCSD >= 1.1.1 is required"
    9 | #error "OpenCSD >= 1.1.1 is required"
      |  ^~~~~
⬢[acme@toolbox perf]$

But the fact that I ask for CORESIGHT=1 should have the build fail then,
i.e. if one explicitely asks for a feature and it can't be built, fail
the whole build.

- Arnaldo