linux-kernel - Re: [patch 1/3] kmsg: Kernel message catalog macros.

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Message-Id: <1218994138.20098.6.camel@localhost>
Date:	Sun, 17 Aug 2008 19:28:58 +0200
From:	Martin Schwidefsky <schwidefsky@...ibm.com>
To:	Tim Hockin <thockin@...kin.org>
Cc:	Rusty Russell <rusty@...tcorp.com.au>,
	linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
	lf_kernel_messages@...ts.linux-foundation.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Michael Holzheu <holzheu@...ibm.com>,
	Gerrit Huizenga <gh@...ibm.com>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Randy Dunlap <randy.dunlap@...cle.com>,
	Jan Kara <jack@...e.cz>, Pavel Machek <pavel@....cz>,
	Sam Ravnborg <sam@...nborg.org>, Joe Perches <joe@...ches.com>,
	Jochen Voß <jochen.voss@...glemail.com>,
	Kunai Takashi <kunai@...ux-foundation.jp>,
	Tim Bird <tim.bird@...sony.com>
Subject: Re: [patch 1/3] kmsg: Kernel message catalog macros.

On Sat, 2008-08-16 at 13:40 -0700, Tim Hockin wrote:
> >> > > Can you hash the format string to generate the id?  6 hex digits should
> >> > > be enough, and your tool can check for clashes.  As it's bad form to have
> >> > > identical strings for different semantics anyway, this seems to make
> >> > > sense.
> 
> > Ok, so  a specialized version of printk will do the work to calculate
> > the hash. Only, what will we do if there ever is a conflict? The message
> > tag has to be unique. The shorter the hash is, the more likely a
> > collision gets. Don't know if 6 hash digits is enough to just ignore the
> > problem.
> 
> And if you ever need to change the text that is in the format string?
> The hash changes.  That seems exactly counter to your goal...

The only problem here is trivial change like typos. Then the hash
changes although the message is semantically still the same. If the
message really changes, its id should change as well. 

-- 
blue skies,
  Martin.

"Reality continues to ruin my life." - Calvin.


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