一个最简单的测试在/dev下生成字符设备的程序

先贴代码：

1. #include <linux/init.h> /* Needed for the macros */
2. #include <linux/kernel.h>
3. #include <linux/module.h> /* Needed for all modules */
4. #include <linux/fs.h>
5. #include <linux/cdev.h>
6. #include <linux/device.h>
8. MODULE_LICENSE("Dual BSD/GPL");
9. MODULE_AUTHOR("ttxgz");
11. int hello_major = 555;
12. int hello_minor = 0;
13. int number_of_devices = 1;
15. int memalloc_major = 111;
16. int memalloc_minor = 1;
18. struct cdev cdev;
19. dev_t dev = 0;
21. struct file_operations hello_fops = {
22. .owner = THIS_MODULE
23. };
25. struct class *my_class;
26. struct class *mem_class;
28. static int __init hello_init(void)
29. {
30. int result;
31. dev = MKDEV (hello_major, hello_minor);
34. /* create your own class under /sysfs */
35. my_class = class_create(THIS_MODULE, "my_class");
36. if(IS_ERR(my_class))
37. {
38. printk("Err: failed in creating class.\n");
39. return -1;
40. }
41. device_create( my_class, NULL, MKDEV(hello_major, hello_minor), NULL, "hello%d",0);
43. mem_class = class_create(THIS_MODULE, "mem_class");
44. device_create( mem_class, NULL, MKDEV(memalloc_major, memalloc_minor), NULL, "memalloc");
46. printk(KERN_ALERT "Hello, world!/n");
47. return 0;
48. }
50. static void __exit hello_exit(void)
51. {
53. dev_t devno = MKDEV (hello_major, hello_minor);
54. device_destroy(my_class, MKDEV(hello_major, 0)); //delete device node under /dev
55. class_destroy(my_class); //delete class created by us
56. unregister_chrdev_region (devno, number_of_devices);
59. devno = MKDEV(memalloc_major,memalloc_minor);
60. device_destroy(mem_class, MKDEV(memalloc_major, memalloc_minor)); //delete device node under /dev
61. class_destroy(mem_class); //delete class created by us
63. printk (KERN_INFO "char driver cleaned up\n");
64. printk(KERN_ALERT "Goodbye, cruel world/n");
65. }
67. module_init(hello_init);
68. module_exit(hello_exit);

makefile是这样的：

1. ifeq ($(KERNELRELEASE),)
3. # Assume the source tree is where the running kernel was built
4. # You should set KERNELDIR in the environment if it''s elsewhere
6. KERNELDIR ?= /lib/modules/$(shell uname -r)/build
8. # The current directory is passed to sub-makes as argument
10. PWD := $(shell pwd)
12. modules:
13. $(MAKE) -C $(KERNELDIR) M=$(PWD) modules

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