On Tue, Jan 20, 2004 at 20:40:37 -0000, Saqib Shaikh wrote:
> Hi
>
> I'm an experienced programmer in userspace, but am relatively new to kernel
> programming. I'm attempting to write a module, and can't find any good
> documentation about what should go in the makefile. In particular, what
> flags are required for the compiler? I've included my first attempt at a
> makefile below:
>
> CC = gcc
> TARGET = acsint
> DEFS = -DLINUX -DMODULE -D__KERNEL__
> INC = -I/usr/src/linux/include
> -I/usr/lib/gcc-lib/i386-redhat-linux/3.2/include -nostdinc
> CFLAGS = -c -O2 -pipe -Wall ${DEFS} ${INC}
>
> ${TARGET}.o: ${TARGET}.c
>
> clean:
> rm -f ${TARGET}.o
>
> Any help appreciated
Should it be an in-tree (ie. integrated with rest of kernel), or
off-tree build.
If you want to do an in-tree build, you will need to fill in appropriate
variables in the kernel Makefile.
If you want to do an off-tree build, you will need to get proper CFLAGS
for kernel. The safest way to do it is to call kernel makefile as
follows:
make -s script "SCRIPT=echo \$(CFLAGS)"
(with -C to kernel source directory etc...)
Then the appropriate command for compiling is:
cc -DLINUX -DMODULE $(CFLAGS) -o $@ $<
And then for linking is:
ld -r -o $@ $+
Note, that the result of linking should have .o suffix. How you call the
intermediate object is up to you.
-------------------------------------------------------------------------------
Jan 'Bulb' Hudec <bulb@ucw.cz>
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