linux-kernel - Re: Immortal CONFIG_DEBUG

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Message-ID: <20081116080344.GA31296@x200.localdomain>
Date:	Sun, 16 Nov 2008 11:03:44 +0300
From:	Alexey Dobriyan <adobriyan@...il.com>
To:	Sam Ravnborg <sam@...nborg.org>
Cc:	viro@...IV.linux.org.uk, zippel@...ux-m68k.org,
	linux-kernel@...r.kernel.org
Subject: Re: Immortal CONFIG_DEBUG_INFO=y

On Sun, Nov 16, 2008 at 08:49:48AM +0100, Sam Ravnborg wrote:
> On Sun, Nov 16, 2008 at 10:42:01AM +0300, Alexey Dobriyan wrote:
> > As known to everybody doing fat builds, banning DEBUG_INFO=y is mandatory,
> > otherwise build is slower and takes much more disk space. And to not
> > accidently enable it, banning it in kconfig:
> > 
> > 	@@ -475,7 +475,7 @@ config DEBUG_BUGVERBOSE
> > 	 
> > 	 config DEBUG_INFO
> > 	 	bool "Compile the kernel with debug info"
> > 	-	depends on DEBUG_KERNEL
> > 	+	depends on DEBUG_KERNEL && DISABLED
> > 	 	help
> > 	           If you say Y here the resulting kernel image will include
> > 	 	  debugging info resulting in a larger kernel image.
> > 
> > This works pretty well -- allmodconfig generates config without DEBUG_INFO and
> > so on, defconfigs also regenerated without it, even if original one in arch/
> > has DEBUG_INFO enabled and so on. Trick also works for other options, like,
> > KALLSYMS_EXTRA_PASS.
> > 
> > Except one case:
> > 
> > 	make ARCH=sh magicpanelr2_defconfig
> > 
> > DEBUG_INFO survives to .config and resulting build runs with -g.
> 
> Because that defconfig does:
> CONFIG_SH_KGDB=y
> 
> and SH_KGDB does:
> 	select DEBUG_INFO

Indeed, thank you for explanation!

> Instead of editing the Kconfig file you should use the KCONFIG_ALLCONFIG trick.

It's not reliable.

The very same select will select DEBUG_INFO as usual.
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