Linux device driver programming-the simplest hellomod

1. download the source code package corresponding to the system kernel version. view the version by uname-r. My is 2632 download command: apt-getinstalllinux-source-2632 I download linux-source-2632tarbz22, configure kernel: tarjxvflinux-so

1. download the source code package corresponding to the system kernel version. view the version by uname-r.

My account is 2.6.32.

Download command: apt-get install linux-source-2.6.32

What I download is linux-source-2.6.32.tar.bz2.

2. configure the kernel:

Tar jxvf linux-source-2.6.32.tar.bz2

Cd linux-source-2.6.32

Make oldconfig # configure the original version

3, compile the kernel (this process takes a long time, after compilation in the linux-source-2.6.32 more than a vmlinux)

Make

4. compilation module

Make modules

5. install the module (the directory/lib/modules/2.6.32.61 + drm33.26 is displayed after the operation)

Make modules_install

6. test

①. Hellomod. c

# Include
 
  
// Initial function change # include
  
   
// Kernel header file # include
   
    
// Module header file MODULE_LICENSE ("GPL"); // prompt that the GNU license static int lkp_init (void) may not exist. // initialize {printk ("Hello, world \ n "); // the module runs in the kernel state. instead of using the printf function in the user State C library function, use the printk function return 0;} static int lkp_cleanup (void) // exit and cleanup functions {printk ("Goodbye, Hello world \ n");} module_init (lkp_init); // driver initialization entry point module_exit (lkp_cleanup ); // call the cleanup_module () function
   
  
 

② Makefile

obj-m :=hellomod.oKERNELDIR=/lib/modules/2.6.32.61+drm33.26/buildPWD :=$(shell pwd)modules:        $(MAKE) -C $(KERNELDIR) M=$(PWD) modulesmodules_install:        $(MAKE) -C $(KERNELDIR) M=$(PWD) modules_install

③ Execute make

Output:

root@master:~/Downloads/.1/lken# makemake -C /lib/modules/2.6.32.61+drm33.26/build M=/root/Downloads/.1/lken modulesmake[1]: Entering directory `/usr/src/linux-source-2.6.32'  Building modules, stage 2.  MODPOST 1 modules  CC      /root/Downloads/.1/lken/hellomod.mod.o  LD [M]  /root/Downloads/.1/lken/hellomod.komake[1]: Leaving directory `/usr/src/linux-source-2.6.32'

The hellomod. ko file is generated in the directory.

④ Insert and view the kernel

Insmod hellomod. ko

Root @ master :~ /Downloads/. 1/lken # lsmod | grep hellomod
Hellomod0 679

⑤ Remove a module

Rmmod hellomod

View Diaries

Tail/var/log/message

Output:

Jan  5 16:18:49 master kernel: [161488.154792] Hello, worldJan  5 16:19:20 master kernel: [161519.197040] Goodbye,Hello world