Linux Device Driver - first Module_88e1111 device or resource busy-优快云博客

本文将指导您如何使用Linux内核源代码开发模块，包括模块的源代码编写、Makefile配置、模块编译、内核加载、输出信息打印及模块移除等步骤。

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At first, you should have one linux kernal source code, and have opened "Enable Loadable module support" in Linux Kernal Configuration GUI by "$ sudo make menuconfig".

1. The source code of the module:

#include <linux/module.h> 
#include <linux/kernel.h> 
#include <linux/init.h>   
MODULE_LICENSE ("GPL");   
static int __init hello_2_init (void) 
{   
printk (KERN_INFO "Hello world\n");  
return 0;
}


static void __exit hello_2_exit (void)
{   
printk (KERN_INFO "Goodbye world\n"); 
}   
module_init (hello_2_init); 
module_exit (hello_2_exit);

2. Makefile

ifeq ($(KERNELRELEASE),) 

#KERNELDIR ?= /home/lht/kernel2.6/linux-2.6.14   
KERNELDIR ?= /lib/modules/$(shell uname -r)/build   
PWD := $(shell pwd)   
modules:
	$(MAKE) -C $(KERNELDIR) M=$(PWD) modules   
modules_install:
	$(MAKE) -C $(KERNELDIR) M=$(PWD) modules_install   
clean:
	rm -rf *.o *~ core .depend .*.cmd *.ko *.mod.c .tmp_versions   
.PHONY: 
	modules modules_install clean  
else      
	obj-m := hello.o 
endi

3. Compile "Hello" module

$ make

$ ls
hello.c hello.c~ hello.ko hello.mod.c hello.mod.o hello.o Makefile modules.order Module.symvers

4. Insert "Hello" module to kernal

$ sudo insmod hello

5. Print module output message that was saved in the kernal message stack

$ sudo dmesg -c

[12104.762170] Hello world

6. Remove the "Hello" module

$ sudo rmmod hello

$ sudo dmesg -c

[12143.629505] Goodbye world