HOWTO compile kernel modules for the kernel 2.6: (编译linux2.6版本内核)

If you want to compile the hello module follow these steps:
Create the Makefile in your directory with the hello.c

obj-m    := hello.o

KDIR    := /lib/modules/$(shell uname -r)/build
PWD    := $(shell pwd)

default:
	$(MAKE) -C $(KDIR) M=$(PWD) modules

Now do a

make

... and the hello.ko is built.

If you get something like this

# make
make: Nothing to be done for `default'.

you need to install the kernel source and compile the kernel first (run "make" at least to the point until all "HOSTCC scripts/" stuff is done - this will configure your kernel and allows external module compilation). Make sure /lib/modules/$(shell uname -r)/build points to your build directory (most likely /usr/src/linux...).
Another reason for the above error can be, that your browser converted the TAB before $(MAKE) to spaces. Make sure there is a TAB before $(MAKE).

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 Install it with install.sh:

#!/bin/sh
install -m 644 hello.ko /lib/modules/`uname -r`/kernel/drivers/hello.ko
/sbin/depmod -a

(adjust the /lib/modules path according to your needs)

Now make a

# modprobe hello 

Or if you don't want to install the module, do this:

# insmod ./hello.ko

..and if your system doesn't freeze you've done it right ;-)

For kernel 2.4, the Makefile would look like this:

TARGET	:= modulename
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

 hello.c

#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>

MODULE_LICENSE("Dual BSD/GPL");

static int hello_init(void)
...{
    printk(KERN_ALERT "hello, world ");
    return 0;
}

static void hello_exit(void)
...{
    printk(KERN_ALERT "goodbye,cruel world ");
}

module_init(hello_init);
module_exit(hello_exit);