Messages in this thread | | | Date | Sat, 4 Apr 1998 20:55:18 -0600 | From | Michael Elizabeth Chastain <> | Subject | Re: Shouldn't SMP be an option? |
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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.
Cheers,
Michael Chastain <mailto:mec@shout.net> "love without fear"
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