Re: [RFC PATCH] kconfig: introduce KCONFIG_* symbols for .c files

[Sam Ravnborg <sam@ravnborg.org>]

On Sat, May 24, 2008 at 09:14:46PM +0100, Jeremy Fitzhardinge wrote:
> Andrew Morton wrote:
> >It could help to get us out of the occasional sticky situation, but it
> >  
> 
> I think if you know you can use the if(KCONFIG_) technique, then one 
> would tend to structure things so that you do it as much as possible.  
> Ideally you'd use CONFIG vars in Makefiles to make code go away 
> entirely, and if (KCONFIG_) in .c files to do conditional compilation.
> 
> >does seem a bit risky.  What happens with Kconfig variables which are
> >just not known about at all with some .configs?
> >
> >Silly example, one could add
> >
> >	if (KCONFIG_DVB_VES1820)
> >
> >to kernel/sched.c and that would work happily until someone sets DVB=n,
> >in which case I assume KCONFIG_DVB_VES1820 doesn't get defined
> >anywhere?
> >
> >A more realistic example might be using an x86-only KCONFIG_* in non-x86
> >code.
> >  
> 
> Well, logically that means that all config vars are always "known", even 
> if they can never be defined.  I don't know what the practicalities of 
> that are: can all Kconfig files everywhere reasonably be scanned to 
> produce the symbol list?

When we have one configuration for the kernel and not as today
where we have one configuration for each architecture (with a lot
of shared files) then it is already taken care of by my (updated) patch.

	Sam