Try to build tutorial for linux device driver - makefile

Question

i am trying to learn how to write device driver on linux. I have looked at several online tutorials. They are simple enough but I have problem compiling it. I got a makefile error at the bottom. I have not done anything to the linux-header-2.6.32-27-generic. It is in the state that it was installed. It may be that it has some dependencies but I have no ideas which one. I am not sure what make is expecting.
I would appreciate any help.
Here is my system info.
Linux rat-desktop 2.6.32-27-generic #49-Ubuntu SMP Wed Dec 1 23:52:12 UTC 2010 i686 GNU/Linux
The include files are in /usr/src/linux-headers-2.6.32-27-generic
rat#rat-desktop:/usr/src/linux-headers-2.6.32-27-generic$ ls
arch firmware Kbuild modules.order security usr
block fs kernel Module.symvers sound virt
crypto include lib net source
Documentation init Makefile samples tools
drivers ipc mm scripts ubuntu
nothing.c
#include <linux/init.h>
#include <linux/module.h>
MODULE_LICENSE("Dual BSD/GPL");
static int __init hello_init(void)
{
printk(KERN_ALERT "Hello,world tapas\n");
return 0;
}
static void __exit hello_exit(void)
{
printk(KERN_ALERT "Good Bye,cruel world\n");
}
module_init(hello_init);
module_exit(hello_exit);
Makefile
obj-m := nothing.o
KDIR = /usr/src/linux-headers-2.6.32-27-generic
all:
$(MAKE) make -C $(KDIR) M=pwd modules
clean:
rm -rf *.o *.ko *.mo.* *.symvers *.order
sudo make
make make -C /usr/src/linux-headers-2.6.32-27-generic M=pwd modules
make[1]: Entering directory `/usr/src/linux-headers-2.6.32-27-generic'
make[1]: *** No rule to make target `make'. Stop.
make[1]: Leaving directory `/usr/src/linux-headers-2.6.32-27-generic'
make: *** [all] Error 2
I used another Makefile which got me a little more detail
obj-m += nothing.o
all:
make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
clean:
make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
rat#rat-desktop:~/deviceDrivers$ sudo make
make -C /lib/modules/2.6.32-27-generic/build M= modules
make[1]: Entering directory `/usr/src/linux-headers-2.6.32-27-generic'
CHK include/linux/version.h
CHK include/linux/utsrelease.h
SYMLINK include/asm -> include/asm-x86
make[2]: *** No rule to make target `kernel/bounds.c', needed by `kernel/bounds.s'. Stop.
make[1]: *** [prepare0] Error 2
make[1]: Leaving directory `/usr/src/linux-headers-2.6.32-27-generic'
make: *** [all] Error 2

Answer 1

In the first Makefile, observe the make command that is being executed in the output when you run sudo make (generally sudo is not required to build the modules) :
make make -C /usr/src/linux-headers-2.6.32-27-generic M=pwd modules
In this case, make is searching for a target named 'make'! Remove the $(MAKE) from the Makefile and try. And also M=pwd option is incorrect!
In the second case, the PWD variable isn't defined. You can define it in the Makefile something like this :
PWD := $(shell pwd)