Re: split-includes

Michael Elizabeth Chastain (mec@shout.net)
Fri, 5 Feb 1999 22:00:43 -0600


Hi Chris,

> Are the files created by the split-includes script actually used yet?

Very much so, but not in the way you probably mean. The C compiler
never sees them. But 'make' uses them for dependencies. Check out
Documentation/smart-config.txt and then look at some '.depend'
files and then come back and ask me questions if you like.

> Is there a reason for this?

Yes. My original design was to migrate in the direction of including
individual files. Then mkdep.c wouldn't need any special magic to
get fine-grained includes, and the kernel-building machinery would be
a little simpler.

There are two problems with this design. The technical problem is
that config options often depend on other config options, so you
can't just #include <config/foo/bar.h> and have it work.

The social problem is like this. Think of the linux kernel community
as a large cluster of hairy SMP systems. Changing anything in the
way people write code requires flushing a huge number of L2 caches
inside people's heads. This is difficult and expensive, so you have
to have a really compelling value proposition to make people want
to change anything in the kbuild process.

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

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