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Re: debug tip after earlycon is closed?

From Masahiro Yamada <yamada.masahiro@socionext.com>
Newsgroups linux.kernel
Subject Re: debug tip after earlycon is closed?
Date 2016-07-27 05:30 +0200
Message-ID <rZnHH-2rc-9@gated-at.bofh.it> (permalink)
References <rZlPA-1a1-1@gated-at.bofh.it> <rZmBX-1Ls-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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Hi Sebastian,


2016-07-27 11:17 GMT+09:00 Sebastian Reichel <sre@kernel.org>:
> Hi,
>
> On Wed, Jul 27, 2016 at 10:23:09AM +0900, Masahiro Yamada wrote:
>> When the kernel fails to boot and its log console is silent,
>> I use earlycon and I often find the cause of error with it.
>>
>> But, I have been wondering if there is an easy-to-use
>> debug tip which is available after earlycon is disabled.
>>
>> I noticed the current mainline would not boot on my ARMv8 board.
>> According to the following log, I am guessing something wrong
>> is happening after the "bootconsole [uniphier0] disabled" log.
>>
>> Is there a good practice to see more log?
>
> Documentation/kernel-parameters.txt
>         keep_bootcon    [KNL]
>                         Do not unregister boot console at start. This is only
>                         useful for debugging when something happens in the window
>                         between unregistering the boot console and initializing
>                         the real console.


I did not know this kernel parameter, and it is exactly what I wanted.
Thanks a lot!


-- 
Best Regards
Masahiro Yamada

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Thread

debug tip after earlycon is closed? Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-07-27 03:30 +0200
  Re: debug tip after earlycon is closed? Sebastian Reichel <sre@kernel.org> - 2016-07-27 04:20 +0200
    Re: debug tip after earlycon is closed? Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-07-27 05:30 +0200
  Re: debug tip after earlycon is closed? Arnd Bergmann <arnd@arndb.de> - 2016-07-27 09:40 +0200
    Re: debug tip after earlycon is closed? Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-07-28 04:10 +0200
      Re: debug tip after earlycon is closed? Arnd Bergmann <arnd@arndb.de> - 2016-07-28 09:50 +0200
        Re: debug tip after earlycon is closed? Russell King - ARM Linux <linux@armlinux.org.uk> - 2016-07-28 14:30 +0200
          Re: debug tip after earlycon is closed? Rabin Vincent <rabin@rab.in> - 2016-08-08 11:10 +0200

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