Date: Tue, 8 Mar 2016 17:30:45 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Dmitry Vyukov <dvyukov@google.com>, Wang Nan <wangnan0@huawei.com>,
        Ingo Molnar <mingo@redhat.com>, LKML <linux-kernel@vger.kernel.org>,
        He Kuang <hekuang@huawei.com>, Alexei Starovoitov <ast@kernel.org>,
        Arnaldo Carvalho de Melo <acme@redhat.com>,
        Brendan Gregg <brendan.d.gregg@gmail.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
        Namhyung Kim <namhyung@kernel.org>, Zefan Li <lizefan@huawei.com>,
        pi3orama@163.com
Subject: Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer
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On Tue, Mar 08, 2016 at 05:27:03PM +0100, Ingo Molnar wrote:
> > > triton:~/go/src/github.com/google/syzkaller> cat perf.cfg
> > > {
> > >         "http": "localhost:50000",
> > >         "workdir": "/home/mingo/go/src/github.com/google/syzkaller/workdir",
> > >         "syzkaller": "/home/mingo/go/src/github.com/google/syzkaller",
> > >         "vmlinux": "-",
> > >         "type": "local",
> > >         "count": 1,
> > >         "procs": 16,
> > >         "nocover": true,

this^^^

> I now get periodic output of:
> 
> fomalhaut:~/go/src/github.com/google/syzkaller> bin/syz-manager -config src/github.com/google/syzkaller/perf.cfg
> 2016/03/08 17:24:07 failed to read config file: open src/github.com/google/syzkaller/perf.cfg: no such file or directory
> fomalhaut:~/go/src/github.com/google/syzkaller> bin/syz-manager -config perf.cfg
> 2016/03/08 17:24:19 loading corpus...
> 2016/03/08 17:24:19 loaded 0 programs
> 2016/03/08 17:24:19 serving http on http://localhost:50000
> 2016/03/08 17:24:19 serving rpc on tcp://127.0.0.1:37006
> 2016/03/08 17:24:34 local-0: saving crash 'BUG: /sys/kernel/debug/kcov is missing (permission denied). Enable CONFIG_KCOV and mount debugfs.' to crash-local-0-1457454274467286949
> 2016/03/08 17:24:34 local-0: lost connection: exit status 1

> is CONFIG_KCOV=y a must-have feature? There's no KCOV support upstream that I can 
> see.

Should have disabled that.