From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: Petr Mladek <pmladek@suse.com>, Dmitry Vyukov <dvyukov@google.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] printk: Add caller information to printk() output.
Date: Sat, 1 Dec 2018 23:44:37 +0900 [thread overview]
Message-ID: <f224bd68-7394-ff70-cad6-d3fbbb3b5f7d@i-love.sakura.ne.jp> (raw)
In-Reply-To: <20181130154024.ls3mntfdr4zvluub@pathway.suse.cz>
On 2018/12/01 0:40, Petr Mladek wrote:
>> Some examples for console output:
>>
>> [ 0.293000] [T1] smpboot: CPU0: Intel(R) Core(TM) i5-4440S CPU @ 2.80GHz (family: 0x6, model: 0x3c, stepping: 0x3)
>> [ 0.299733] [T1] Performance Events: Haswell events, core PMU driver.
>> [ 2.813808] [T35] clocksource: Switched to clocksource tsc
>> [ 2.893984] [C0] random: fast init done
> ^
>
> Please, remove the space between the timestamp and the from field.
This space was emitted by print_time(). Do we want to modify print_time()
not to emit this space if the from field is printed?
If we modify print_time(), I think that the leading spaces inserted by "%5lu"
makes little sense, for "%5lu" is too small for systems with uptime >= 1.16 days
and parsers after all cannot assume fixed length for the timestamp field. Then,
we could change from "%5lu.%06lu" to "%lu.%06lu" so that parsers (like /bin/awk)
can get prefix part using white spaces as a delimiter.
If we want to reduce space, do we want to do like
[0.293000@T1] smpboot: CPU0: Intel(R) Core(TM) i5-4440S CPU @ 2.80GHz (family: 0x6, model: 0x3c, stepping: 0x3)
[0.299733@T1] Performance Events: Haswell events, core PMU driver.
[2.813808@T35] clocksource: Switched to clocksource tsc
[2.893984@C0] random: fast init done
(if printk_time = true) or
[@T1] smpboot: CPU0: Intel(R) Core(TM) i5-4440S CPU @ 2.80GHz (family: 0x6, model: 0x3c, stepping: 0x3)
[@T1] Performance Events: Haswell events, core PMU driver.
[@T35] clocksource: Switched to clocksource tsc
[@C0] random: fast init done
(if printk_time = false) ?
Dmitry, what format/delimiter is convenient for parsing by syzbot?
>> @@ -1037,6 +1054,9 @@ void log_buf_vmcoreinfo_setup(void)
>> VMCOREINFO_OFFSET(printk_log, len);
>> VMCOREINFO_OFFSET(printk_log, text_len);
>> VMCOREINFO_OFFSET(printk_log, dict_len);
>> +#ifdef CONFIG_PRINTK_FROM
>> + VMCOREINFO_OFFSET(printk_log, from_id);
>> +#endif
>
> The crash tool would need to be updated if anyone wanted to read
> the log from the extended structure. Well, it might be done later
> if people start using it more widely.
Since syzbot can utilize output from only normal consoles, I can
keep extended records unmodified for now.
>
> I think about adding one more filed "u8 version". It would help
> to solve the external compatibility in the long term.
/dev/kmsg format allows adding more fields, but that format did not define
how to tell what fields are there. If fields are conditionally added by
kernel config options, I don't think that "u8 version" field helps.
Unless we add fields unconditionally, we will need to use $name=$value
(where $name and $value must not contain ',' and ';') representation.
> Anyway, I like this feature. It is compatible with /dev/kmsg
> format. dmesg works well. It helps to sort any mixed output
> from both full and continuous lines.
OK, let's refine this approach.
next prev parent reply other threads:[~2018-12-01 14:44 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-24 7:37 [PATCH] printk: Add caller information to printk() output Tetsuo Handa
2018-11-30 15:40 ` Petr Mladek
2018-12-01 14:44 ` Tetsuo Handa [this message]
2018-12-02 11:23 ` Tetsuo Handa
2018-12-04 2:02 ` Sergey Senozhatsky
2018-12-04 10:16 ` Tetsuo Handa
2018-12-04 10:38 ` Sergey Senozhatsky
2018-12-04 15:31 ` Petr Mladek
2018-12-03 15:06 ` Petr Mladek
2018-12-03 21:10 ` Tetsuo Handa
2018-12-04 15:27 ` Petr Mladek
2018-12-05 10:42 ` Tetsuo Handa
2018-12-05 11:50 ` Sergey Senozhatsky
2018-12-07 4:58 ` Tetsuo Handa
2018-12-07 5:31 ` Sergey Senozhatsky
2018-12-10 13:09 ` Petr Mladek
2018-12-10 14:01 ` Tetsuo Handa
2018-12-11 10:26 ` Tetsuo Handa
2018-12-12 2:25 ` Sergey Senozhatsky
2018-12-12 2:29 ` Sergey Senozhatsky
2018-12-13 12:18 ` Petr Mladek
2018-12-13 12:42 ` Sergey Senozhatsky
2018-12-17 14:54 ` Petr Mladek
2018-12-17 15:40 ` Sergey Senozhatsky
2018-12-17 21:05 ` Tetsuo Handa
2018-12-18 8:39 ` Petr Mladek
2018-12-18 8:58 ` Sergey Senozhatsky
2019-01-02 16:09 ` Dmitry Vyukov
2019-01-03 18:27 ` Dmitry Vyukov
2019-01-04 7:33 ` Fengguang Wu
2019-01-11 19:34 ` Kevin Hilman
2019-01-10 11:27 ` Tetsuo Handa
2018-12-18 8:55 ` Sergey Senozhatsky
2018-12-18 10:01 ` Petr Mladek
2018-12-18 10:10 ` Sergey Senozhatsky
2019-03-21 2:59 ` Michael Ellerman
2019-03-21 10:20 ` Petr Mladek
2019-03-22 0:48 ` Michael Ellerman
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