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From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Fri, 18 May 2018 15:08:06 +0200
Message-ID: <CACT4Y+aFO+yZ7ovkxJOJfz=JgsE3yr+ywLQ9kVUrOHYMBgfWdg@mail.gmail.com>
Subject: Re: [PATCH] printk: inject caller information into the body of message
To:     Petr Mladek <pmladek@suse.com>
Cc:     Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
        Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        syzkaller <syzkaller@googlegroups.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Fengguang Wu <fengguang.wu@intel.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>
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On Fri, May 18, 2018 at 2:54 PM, Petr Mladek <pmladek@suse.com> wrote:
> On Fri 2018-05-18 14:25:57, Dmitry Vyukov wrote:
>> > On Thu 2018-05-17 20:21:35, Sergey Senozhatsky wrote:
>> >> Dunno...
>> >> For instance, can we store context tracking info as a extended record
>> >> data? We have that dict/dict_len thing. So may we can store tracking
>> >> info there? Extended records will appear on the serial console /* if
>> >> console supports extended data */ or can be read in via devkmsg_read().
>>
>> What consoles do support it?
>> We are interested at least in qemu console, GCE console and Android
>> phone consoles. But it would be pity if this can't be used on various
>> development boards too.
>
> Only the netconsole is able to show the extended (dict)
> information at the moment. Search for CON_EXTENDED flag.

Then we won't be able to use it. And we can't pipe from devkmsg_read
in user-space, because we need this to work when kernel is broken in
various ways...