Hi Brendan,
Here's the historical rationale on the "touch" commands.
Suppose that foo.c includes bar1.h, bar1.h includes bar2.h.
Suppose that you edit bar2.h, or more likely, you apply a patch
that changes bar2.h. Either way, you do something that updates bar2.h.
The way that the dependencies are set up is:
foo.o: foo.c bar1.h
gcc -D __KERNEL__ ... -o foo.o foo.c
bar1.h: bar2.h
touch bar1.h
So when you update bar2.h, then Make will update the timestamp on
bar1.h by touching it (causing you the problem with read-only files),
which causes foo.o to be out-of-date and rebuilt.
Suppose that you nuke out that "touch" command. And then you update
bar2.h. Then bar1.h is out of date, and foo.o will be rebuilt. And
the next time you run Make, bar1.h will still be out-of-date, and
it will be rebuilt, again and again.
The function of the "touch" command is to provide that when you update
bar2.h, foo.o is going to get built only once, not every time you run
Make forever more.
There are a couple of ways to fix this:
. the right way: change the dependencies to:
foo.o: foo.c bar1.h bar2.h
gcc -D __KERNEL__ ... -o foo.o foo.c
unfortunately you can't get there from here easily.
. skanky way #1: change your path to add a directory that contains a
shell script named "touch" that just returns successfully without
doing anything.
. skanky way #2: change the source code in scripts/mkdep.c to replace
the "touch" command with a ":" command (a shell no-op).
I recommend experimenting with skanky way #2. The makefile system
will still have correct dependencies. If you update the header files
a lot (such as by applying patches), you will see that it builds too
much on repeated builds, but it will never fail to build a necessary
file.
If an entire kernel build takes only a couple of minutes in your
environment then this might be good enough for you forever.
(The files aren't getting updated all that often anyways if you are
seeing them as read-only).
CML2 is outside this whole area. You would be looking for Keith Owen's
makefile rewrite, which addresses this issue.
Michael Elizabeth Chastain
<mailto:[EMAIL PROTECTED]>
"love without fear"
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