Re: Shouldn't SMP be an option?
H. Peter Anvin (hpa@transmeta.com)
Sat, 4 Apr 1998 19:32:34 -0800 (PST)
> Hi Peter,
>
> > Yes, but I think a lot of things still #include <linux/config.h>,
> > which AFAIK is the "old style".
>
> Aha, let me illuminate you (and anyone else on the list that cares). :)
>
> _Everything_ still uses #include <linux/config.h>.
>
> There's a program, scripts/mkdep.c, that takes files and computes
> dependencies for them. The classical way to do this is to list all
> the #include's.
>
> Werner Almesberger had a bright idea: he changed mkdep.c so that when
> a file #include's <linux/config.h>, it *does not* have a dependency on
> include/linux/config.h! Instead, it has a lot of little dependencies on
> little file. So if foo.c uses CONFIG_FOO_1 and CONFIG_FOO_2, it actually
> has a dependency on include/config/foo/1.h and include/config/foo/2.h.
>
> All these files are auto-generated and when you run 'make
> config/oldconfig/menuconfig/xconfig', only the configuration options
> that change get their little files regenerated.
>
> Try it, take a 2.1.9X kernel, build it, add or subtract a few drivers,
> build it again, watch what happens. Check out source/mkdep.c,
> Documentation/smart-config.txt, and some of the generated .depend files.
>
Gotcha. This makes a lot more sense now.
-hpa
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