HelloWorld 模块

helloworld.c 代码

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

MODULE_LICENSE("Dual BSD/GPL");

static int hello_init(void)
{
        printk(KERN_ALERT "Hello world\n");
        return ;
}

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

module_init(hello_init);
module_exit(hello_exit);

Makefile 代码

 obj-m := helloworld.o

 CURRENT_DIR :=$(shell pwd)

 KERNEL_DIR := /usr/src/linux-headers-$(shell uname -r)

 all:
         $(MAKE) -C $(KERNEL_DIR) M=$(CURRENT_DIR) modules

 clean:
         rm -rf %.o

执行make

 ryan@Ryan-pc:/data1/Ryan/demo/helloworld$ make
 make -C /usr/src/linux-headers-3.13.--generic  M=/data1/Ryan/demo/helloworld modules
 make[]: Entering directory `/usr/src/linux-headers-3.13.--generic'
   Building modules, stage .
   MODPOST  modules
 make[]: Leaving directory `/usr/src/linux-headers-3.13.--generic'

加载模块

 ryan@Ryan-pc:/data1/Ryan/demo/helloworld$ sudo insmod helloworld.ko
 ryan@Ryan-pc:/data1/Ryan/demo/helloworld$ 

dmesg查看

 ryan@Ryan-pc:/data1/Ryan/demo/helloworld$ dmesg

 [178401.813566] sr :::: [sr0] Device not ready
 [178401.813570] sr :::: [sr0]
 [178401.813571] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
 [178401.813572] sr :::: [sr0]
 [178401.813573] Sense Key : Not Ready [current]
 [178401.813575] sr :::: [sr0]
 [178401.813577] Add. Sense: Medium not present - tray closed
 [178401.813579] sr :::: [sr0] CDB:
 [178401.813580] Read():      2f
 [178401.813584] end_request: I/O error, dev sr0, sector
 [179614.794066] helloworld: module verification failed: signature and/or  required key missing - tainting kernel
 [179614.794552] Hello world
 [180458.268623] goodbye,cruel world
 [180514.941519] Hello world
 [180549.136795] goodbye,cruel world
 [181244.193514] Hello world

卸载模块

 ryan@Ryan-pc:/data1/Ryan/demo/helloworld$ sudo rmmod helloworld
 ryan@Ryan-pc:/data1/Ryan/demo/helloworld$