Subject: Re: [RFC] move __devinit or __init printk constant format strings
 to __devinitconst or __initdata?
From: Matt Mackall <mpm@selenic.com>
To: Joe Perches <joe@perches.com>
Cc: linux-embedded@vger.kernel.org, linux-kernel@vger.kernel.org,
       Paul Gortmaker <paul.gortmaker@windriver.com>,
       David Woodhouse <dwmw2@infradead.org>, Tim Bird <tim.bird@am.sony.com>
In-Reply-To: <1248213403.31365.343.camel@Joe-Laptop.home>
References: <1248211253.31365.337.camel@Joe-Laptop.home>
	 <1248212925.10466.143.camel@calx>
	 <1248213403.31365.343.camel@Joe-Laptop.home>
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Date: Tue, 21 Jul 2009 17:57:24 -0500
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On Tue, 2009-07-21 at 14:56 -0700, Joe Perches wrote:
> On Tue, 2009-07-21 at 16:48 -0500, Matt Mackall wrote:
> > On Tue, 2009-07-21 at 14:20 -0700, Joe Perches wrote:
> > > Is moving constant string formats to __devinitconst or __initdata
> > > useful for embedded environments?
> > > As in:
> > > #define printk_section(section, fmt, ...)				\
> > > ({ static const section char __fmt[] = fmt; printk(__fmt, ##__VA_ARGS__); })
> > > #define pr_err_section(section, fmt, ...) \
> > > 	printk_section(section, KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
> > > with a use of:
> > > static int __devinit foo_probe(struct platform_device *pdev)
> > > {
> > > 	if (bar())
> > > 		pr_err_section(__devinitconst,
> > > 			       "A long error message\n");
> > > }
> 
> > Interesting notion, but not worth the trouble in my mind. I think it's
> > more worthwhile to look into automatic such stuff in the build somehow.
> 
> I think it's not possible today to get gcc to mark
> the format strings without source modification.

Yep, that's why I specifically said 'build'. It can probably be done in
a post-processing step with some ELF wizardry. 

> It's pretty easy to script a source conversion.

And that script has to be run how often? I don't think people will find
the churn (and general extra ugliness) acceptable. For a typical
stripped-down embedded kernel, the amount of gain here will be fairly
minimal. I'd be surprised if you got as much as 1K out of it.

-- 
http://selenic.com : development and support for Mercurial and Linux


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