linux-kernel - Re: [PATCH] Translate asm version of ELFNOTE macro into preprocessor macro

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Date:	Wed, 23 Aug 2006 10:47:46 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
CC:	Ian Campbell <Ian.Campbell@...Source.com>,
	Andrew Morton <akpm@...l.org>,
	Virtualization <virtualization@...ts.osdl.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Translate asm version of ELFNOTE macro into	preprocessor
 macro

Eric W. Biederman wrote:
> Jeremy Fitzhardinge <jeremy@...p.org> writes:
>
>   
>> Ian Campbell wrote:
>>     
>>>> OK, seems reasonable.  Eric Biederman solved this by having NOTE/ENDNOTE (or
>>>> something like that) in his "bzImage with ELF header" patch, but I don't
>>>> remember it being used in any way which is incompatible with using a CPP
>>>> macro.
>>>>
>>>>         
>>> I can't find that patch, does NOTE/ENDNOTE just do the push/pop .note
>>> section?
>>>
>>> That would solve the problem with the first argument of the macro being
>>> a string but the final argument could still be for .asciz note contents.
>>>
>>>       

I remember now why I decided to use the assembler macro rather than 
cpp.  The macro names the section after the note name (".note.NAME"), 
and it needs to be quoted so that the name can have spaces and other 
characters which would otherwise upset the assembler.  I couldn't work 
out a clean way to do this with the C preprocessor, since "as" doesn't 
support string concatenation like C does.


> I don't expect it to be much more cumbersome, as two pieces, and you need the extra
> alignment at the end to ensure each not entry is 4 byte aligned. 

Isn't it enough that each entry start have the alignment?  But you need 
some kind of end marker to get the size of the desc field regardless.


>  Being able to
> push and pop a section wouldn't hurt either. 

Yes, I think having each note contain its own .pushsection/popsection is 
the cleaner way of doing it.


    J
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