Re: [rfc] __SMP__ vs. CONFIG_SMP

Michael Elizabeth Chastain (mec@shout.net)
Sat, 25 Dec 1999 21:12:43 -0600

All the __SMP__ are historical. The reason for it was subtle:
suppose every file that needs __SMP__ includes <linux/config.h>.
Then about 95% of the entire kernel would depend on config.h, and
if the user were to re-configure and changes anything, that would
cause a lot of compilation. That was Linus's stated reasoning.

Two things happened. First, about 95% of the kernel source files
depend on <linux/config.h> anyways, regardless of SMP settings.
Second, the kernel now has fine-grained CONFIG_* dependencies,
which took care of the problem Linus was worried about.

I would be in favor of patches to change the existing usages of __SMP__
to CONFIG_SMP, except for the include/ directory. But I think
global cleanup patches are better in 2.5.1 than the pre-2.4 series
which is almost here.

But if you want to write up a partial patch (like arch/i386 and
include/i386) and submit it to Linus and get his opinion, go for it.

Michael Elizabeth Chastain
<mailto:mec@shout.net>
"love without fear"

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