#ifdef usage (was Re: PPC32: Fix the floppy driver, on CONFIG_NOT_COHERENT_CACHE.

[Valdis . Kletnieks]

On Mon, 05 Jan 2004 17:07:23 +0100, Andreas Schwab said:
> Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> writes:
> 
> > On Fri, 2 Jan 2004, Linux Kernel Mailing List wrote:
> >> +#if CONFIG_NOT_COHERENT_CACHE
> >    ^^^
> > Shouldn't this be #ifdef?
> 
> Doesn't matter. Config variables are always either defined to 1 or not
> defined at all (which is equivalent to 0 in #if).

It makes life a lot simpler for those who compile with -Wundef, which is why
I did a bunch of cleanup back around 2.5.6mumble or so.  It also found a real
bug where '#if A | B | C'  and there was a typo in B.  There's also a few
places where code used '#if LINUX_VERSION_CODE > NNNN' without
doing a #include of version.h - fortunately for us, all the cases of *that* happened
to do the right thing when using the implied zero.

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