Primeiro módulo de kernel

Transcript

1. Escreva seu primeiro MÓDULO DE KERNEL (LINUX)
2. Em quatro atos • Hello World! • Character driver • Miscellaneous driver • Ramdisk
3. 0 – Hello World • Olá mundo! • Diego Ramos Ruggeri • http://vai.la/62u3
4. 0 – Hello World • Linux é monolítico • Módulos carregados em tempo de execução • Ciclo de vida • Básico: Inicializar e Limpar
5. 0 – Hello World Porque? • Hardware livre • Entender o Linux • OOP em C • Projeto de software livre
6. static int __init hello_module(void) { printk(KERN_INFO "Hello World!\n"); return 0; } static void __exit goodbye_module(void) { printk(KERN_INFO "Adios\n"); } module_init(hello_module); module_exit(goodbye_module); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Diego Ruggeri"); MODULE_DESCRIPTION("Hello World module");
7. 0 – Hello World obj-m += hello.o all: make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules clean: make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
8. 0 – Hello World • modinfo • insmod • lsmod • rmmod • dmesg
9. 1 – Char Dev • ioctls • net • /dev • /sys • /dev • Block device • Character device • Major Minor
10. static struct file_operations fops = { .read = device_read, .write = device_write, .open = device_open, .release = device_release }; static int __init hello_module(void) { major = register_chrdev(0, DEVICE, &fops); /* … */ } static void __exit goodbye_module(void) { unregister_chrdev(major, DEVICE); }
11. 2 – Misc Dev • mknod /dev/fisl15 c $MAJOR $MINOR • udev • Miscellaneous API
12. static struct file_operations fops = { /*...*/ }; static struct miscdevice mdev = { .minor = MISC_DYNAMIC_MINOR, .name = DEVICE, .fops = &fops, }; static int __init hello_module(void) { misc_register(&mdev) /* … */ } static void __exit goodbye_module(void) { misc_deregister(&mdev); }
13. 3 - Ramdisk • Char device + • Misc api + • Aloca memória (slab) + • open, close, read, write
14. static int __init hello_module(void) { disk = (char*) kzalloc(DISK_SIZE * sizeof(char), GFP_KERNEL); /*…*/ } static void __exit goodbye_module(void) { kfree(disk); /*...*/ }
15. static ssize_t device_read(struct file *filp, char *buffer, size_t length,loff_t * offset) { /*...*/ copy_to_user(buffer, message, len); /*...*/ } static ssize_t device_write(struct file *filp, const char *buff, size_t len, loff_t * off) { copy_from_user(disk, buff, len) }
16. Obrigado diego@ruggeri.net.br http://github.com/diegor2