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Date: Fri, 11 Sep 2015 18:16:47 +0200
From: Jiri Olsa <jolsa@redhat.com>
To: Namhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>, Arnaldo Carvalho de Melo <acme@kernel.org>,
        lkml <linux-kernel@vger.kernel.org>, David Ahern <dsahern@gmail.com>,
        Ingo Molnar <mingo@kernel.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Matt Fleming <matt@codeblueprint.co.uk>,
        =?iso-8859-1?Q?Rapha=EBl?= Beamonte <raphael.beamonte@gmail.com>
Subject: Re: [PATCH 5/5] perf tools: Enhance parsing events tracepoint error
 output
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On Sat, Sep 12, 2015 at 01:09:31AM +0900, Namhyung Kim wrote:
> Hi Jiri,
> 
> On Thu, Sep 10, 2015 at 10:05:37AM +0200, Jiri Olsa wrote:
> > On Thu, Sep 10, 2015 at 04:00:30PM +0900, Namhyung Kim wrote:
> > > On Mon, Sep 07, 2015 at 10:38:07AM +0200, Jiri Olsa wrote:
> > > > Enhancing parsing events tracepoint error output. Adding
> > > > more verbose output when the tracepoint is not found or
> > > > the tracing event path cannot be access.
> > > > 
> > > >   $ sudo perf record -e sched:sched_krava ls
> > > >   event syntax error: 'sched:sched_krava'
> > > >                        \___ unknown tracepoint
> > > > 
> > > >   Error:  File /sys/kernel/debug/tracing//tracing/events/sched/sched_krava not found.
> > > >   Hint:   Perhaps this kernel misses some CONFIG_ setting to enable this feature?.
> > > > 
> > > >   Run 'perf list' for a list of valid events
> > > >   ...
> > > > 
> > > >   $ perf record -e sched:sched_krava ls
> > > >   event syntax error: 'sched:sched_krava'
> > > >                        \___ can't access trace events
> > > > 
> > > >   Error:  No permissions to read /sys/kernel/debug/tracing//tracing/events/sched/sched_krava
> > > >   Hint:   Try 'sudo mount -o remount,mode=755 /sys/kernel/debug'
> > > 
> > > What about tracefs?  On my system, tracefs is mounted on
> > > /sys/kernel/debug/tracing thus I cannot access trace events after
> > > remounting debugfs with mode=755.
> > 
> > right, patch below keeps the actual mount and
> > display proper info.. could you please try?
> 
> Sure, this patch displays the proper tracefs mountpoint.  But it also

thanks

> has a problem - if tracefs is mounted under debugfs, the access mode
> of debugfs also affects, so in this case I had to change it both for
> debugfs and tracefs..


hum, I wonder the error message needs to be that smart..

jirka