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From: Petr Mladek <pmladek@suse.com>
To: Dmitry Safonov <dima@arista.com>
Cc: linux-kernel@vger.kernel.org,
	Dmitry Safonov <0x7f454c46@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	John Ogness <john.ogness@linutronix.de>,
	Sergey Senozhatsky <senozhatsky@chromium.org>,
	Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH v2 2/2] printk: Add printk.console_verbose boot parameter
Date: Fri, 30 Jul 2021 13:00:48 +0200	[thread overview]
Message-ID: <YQPb4LGzj+NuZ7qL@alley> (raw)
In-Reply-To: <20210713011511.215808-3-dima@arista.com>

On Tue 2021-07-13 02:15:11, Dmitry Safonov wrote:
> console_verbose() increases console loglevel to CONSOLE_LOGLEVEL_MOTORMOUTH,
> which provides more information to debug a panic/oops.
> 
> Unfortunately, in Arista we maintain some DUTs (Device Under Test) that
> are configured to have 9600 baud rate. While verbose console messages
> have their value to post-analyze crashes, on such setup they:
> - may prevent panic/oops messages being printed
> - take too long to flush on console resulting in watchdog reboot
> 
> In all our setups we use kdump which saves dmesg buffer after panic,
> so in reality those extra messages on console provide no additional value,
> but rather add risk of not getting to __crash_kexec().
> 
> Provide printk.console_verbose boot parameter, which allows to switch off
> printk being verbose on oops/panic/lockdep (making it boot parameter
> instead of compile-option suggested-by Petr).
> 
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: John Ogness <john.ogness@linutronix.de>
> Cc: Petr Mladek <pmladek@suse.com>
> Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Signed-off-by: Dmitry Safonov <dima@arista.com>

Reviewed-by: Petr Mladek <pmladek@suse.com>
Tested-by: Petr Mladek <pmladek@suse.com>

Best Regards,
Petr

  parent reply	other threads:[~2021-07-30 11:00 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-13  1:15 [PATCH v2 0/2] printk: Add printk.console_verbose boot param Dmitry Safonov
2021-07-13  1:15 ` [PATCH v2 1/2] printk: Remove console_silent() Dmitry Safonov
2021-07-21 14:15   ` Petr Mladek
2021-07-13  1:15 ` [PATCH v2 2/2] printk: Add printk.console_verbose boot parameter Dmitry Safonov
2021-07-21 14:46   ` Petr Mladek
2021-07-26 13:37     ` Dmitry Safonov
2021-07-30 11:00   ` Petr Mladek [this message]
2021-07-30 11:01 ` [PATCH v2 0/2] printk: Add printk.console_verbose boot param Petr Mladek

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