linux-kernel - Re: [PATCH v3 3.18-rc3] kdb: Avoid printing KERN

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Date:	Fri, 07 Nov 2014 11:03:27 -0800
From:	Joe Perches <joe@...ches.com>
To:	Daniel Thompson <daniel.thompson@...aro.org>
Cc:	Jason Wessel <jason.wessel@...driver.com>,
	linux-kernel@...r.kernel.org, kgdb-bugreport@...ts.sourceforge.net,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...hat.com>, patches@...aro.org,
	linaro-kernel@...ts.linaro.org,
	John Stultz <john.stultz@...aro.org>,
	Sumit Semwal <sumit.semwal@...aro.org>, stable@...r.kernel.org
Subject: Re: [PATCH v3 3.18-rc3] kdb: Avoid printing KERN_ levels to consoles

On Fri, 2014-11-07 at 18:47 +0000, Daniel Thompson wrote:
> Currently when kdb traps printk messages then the raw log level prefix
> (consisting of '\001' followed by a numeral) does not get stripped off
> before the message is issued to the various I/O handlers supported by
> kdb. This causes annoying visual noise as well as causing problems
> grepping for ^. It is also a change of behaviour compared to normal usage
> of printk() usage. For example <SysRq>-h ends up with different output to
> that of kdb's "sr h".
> 
> This patch addresses the problem by stripping log levels from messages
> before they are issued to the I/O handlers. printk() which can also
> act as an i/o handler in some cases is special cased; if the caller
> provided a log level then the prefix will be preserved when sent to
> printk().
> 
> The addition of non-printable characters to the output of kdb commands is a
> regression, albeit and extremely elderly one, introduced by commit
> 04d2c8c83d0e ("printk: convert the format for KERN_<LEVEL> to a 2 byte
> pattern"). Note also that this patch does *not* restore the original
> behaviour from v3.5. Instead it makes printk() from within a kdb command
> display the message without any prefix (i.e. like printk() normally does).

This looks nicer.  Thanks Daniel.

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