== How do I compile a Linux kernel module? ==

You have to write a Makefile. The Makefile is a standard one and depends on the kernel version. Do not try to make your own Makefile, use the Linux kernel infrastructure, as explained below.

== Standard Makefile for 4.0 and later kernels ==

{{{
obj-m := name_of_module.o

clean-files := *.o *.ko *.mod.c
}}}

and then use:

{{{
cd path/to/external_module
make -C /path/to/kernel/source M=$PWD
}}}

== Standard Makefile for 2.6 kernels ==

{{{
obj-m := name_of_module.o

all:
	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules

clean:
	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
}}}

For more informations, see [[http://lwn.net/images/pdf/LDD3/ch02.pdf|Linux Device Drivers, Building and Running Modules]], and [[http://lwn.net/Articles/21823/|Driver porting: compiling external modules]].

== Standard Makefile for 2.4 (and <=) kernels ==

{{{
TARGET := module_name
INCLUDE := -I/lib/modules/`uname -r`/build/include
CFLAGS := -O2 -Wall -DMODULE -D__KERNEL__ -DLINUX
CC := gcc

${TARGET}.o: ${TARGET}.c
	$(CC) $(CFLAGS) ${INCLUDE} -c ${TARGET}.c

}}}

Once the module is compiled, you can load it with the following command :
{{{
insmod module.[ko|o]
}}}