linux-kernel - Re: [patch 1/3] Add BSS to resource tree

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Message-ID: <20071018221813.GA23801@uranus.ravnborg.org>
Date:	Fri, 19 Oct 2007 00:18:13 +0200
From:	Sam Ravnborg <sam@...nborg.org>
To:	Andi Kleen <ak@...e.de>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Bernhard Walle <bwalle@...e.de>, linux-kernel@...r.kernel.org,
	kexec@...ts.infradead.org, vgoyal@...ibm.com
Subject: Re: [patch 1/3] Add BSS to resource tree

On Fri, Oct 19, 2007 at 12:00:48AM +0200, Andi Kleen wrote:
> On Thu, Oct 18, 2007 at 11:58:27PM +0200, Sam Ravnborg wrote:
> > On Thu, Oct 18, 2007 at 11:48:37PM +0200, Andi Kleen wrote:
> > > > > +extern char _text[], _end[], _etext[], _edata[], _bss[];
> > > > 
> > > > These should be in a header file.
> > > 
> > > Normally the "no externs in .c" rule doesn't apply to assembler or linker 
> > > script defined labels. That's because the point of the header file is to 
> > > type check them, but there is nothing to type check here.
> > 
> > For linker generated symbols we have sections.h for this purpose.
> > The above symbols are all available if we do an:
> > #include <asm/sections.h>
> > 
> > This is the right fix in this case.
> 
> The problem is that they're often the wrong type here. E.g. wrong signedness 
> etc. I ran into problems in the past where using this required ugly casts.

But then we should fix them instead of working around the problem - no?

Grepping for _text shows that there are plenty of different ways to declare
that symbol extern - this does not look correct.

And I recall that extern char sym[] is considered correct by binutils 
people - but I'm not 100% sure and google did not give me an appropriate hit.

	Sam
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