Ubuntu 10.04 加载/卸载 自定义 module

hello.c

// Defining __KERNEL__ and MODULE allows us to access kernel-level code not usually available to userspace programs.
#undef __KERNEL__
#define __KERNEL__
 
#undef MODULE
#define MODULE
 
// Linux Kernel/LKM headers: module.h is needed by all modules and kernel.h is needed for KERN_INFO.
#include <linux/module.h>    // included for all kernel modules
#include <linux/kernel.h>    // included for KERN_INFO
#include <linux/init.h>        // included for __init and __exit macros
 
static int __init hello_init(void)
{
    printk(KERN_INFO "Hello world!\n");
    return 0;    // Non-zero return means that the module couldn't be loaded.
}
 
static void __exit hello_cleanup(void)
{
    printk(KERN_INFO "Cleaning up module.\n");
}
 
module_init(hello_init);
module_exit(hello_cleanup);

Makefile

obj-m := hello.o
KDIR := /lib/modules/$(shell uname -r)/build
PWD := $(shell pwd)
 
all:
$(MAKE) -C $(KDIR) M=$(PWD) modules
 
clean:
$(MAKE) -C $(KDIR) M=$(PWD) clean

执行命令: make

你也许会得到如下错误：

In file included from /usr/src/linux-headers-2.6.32-38-generic/include/linux/list.h:6,
                 from /usr/src/linux-headers-2.6.32-38-generic/include/linux/module.h:9,
                 from hello_module.c:1:
/usr/src/linux-headers-2.6.32-38-generic/include/linux/prefetch.h:14:27: error: asm/processor.h: No such file or directory
/usr/src/linux-headers-2.6.32-38-generic/include/linux/prefetch.h:15:23: error: asm/cache.h: No such file or directory
In file included from /usr/src/linux-headers-2.6.32-38-generic/include/linux/module.h:9,
                 from hello_module.c:1:
/usr/src/linux-headers-2.6.32-38-generic/include/linux/list.h:7:24: error: asm/system.h: No such file or directory
In file included from /usr/src/linux-headers-2.6.32-38-generic/include/linux/kernel.h:11,
                 from /usr/src/linux-headers-2.6.32-38-

......

你需要做如下操作：

Install and prepare module-assistant.

$ sudo -i
$ apt-get install module-assistant
$ m-a prepare


$  sudo apt-get install build-essential linux-headers-$(uname -r)

然后再次输入命令：make

$ make
make -C /lib/modules/2.6.32-38-generic/build M=/home/jerikc/studydir/linux/module modules
make[1]: Entering directory `/usr/src/linux-headers-2.6.32-38-generic'
  CC [M]  /home/jerikc/studydir/linux/module/hello.o
  Building modules, stage 2.
  MODPOST 1 modules
  CC      /home/jerikc/studydir/linux/module/hello.mod.o
  LD [M]  /home/jerikc/studydir/linux/module/hello.ko
make[1]: Leaving directory `/usr/src/linux-headers-2.6.32-38-generic'

OK，成功得到hello.ko，下面进行测试：

加载module：

$ sudo insmod hello.ko

验证：

$ tail /var/log/syslog

Aug 25 12:29:07 ubuntu dhclient: DHCPREQUEST of 192.168.10.129 on eth0 to 192.168.10.254 port 67
Aug 25 12:29:07 ubuntu dhclient: DHCPACK of 192.168.10.129 from 192.168.10.254
Aug 25 12:29:07 ubuntu dhclient: bound to 192.168.10.129 -- renewal in 865 seconds.
Aug 25 12:33:32 ubuntu kernel: [ 1886.549673] Hello world!

或者使用lsmod查看module信息：

$ lsmod
Module                  Size  Used by
hello                    596  0 
...                      ...  ...

卸载module：

$ sudo rmmod hello

$ tail /var/log/syslog

Aug 25 12:43:32 ubuntu dhclient: DHCPREQUEST of 192.168.10.129 on eth0 to 192.168.10.254 port 67
Aug 25 12:43:32 ubuntu dhclient: DHCPACK of 192.168.10.129 from 192.168.10.254
Aug 25 12:43:32 ubuntu dhclient: bound to 192.168.10.129 -- renewal in 702 seconds.
Aug 25 12:51:07 ubuntu kernel: [ 2939.379275] Cleaning up module.

实验完毕!