慢慢学Linux驱动开发，第六篇，2.6.38版本下LDD3驱动的编译
这两天一直看LDD3，看的很爽，似懂非懂的样子，今天开始编译例程代码scull的时候，悲剧很大，折腾了很久，主要是我Ubuntu11.04的内核版本是2.6.38，而例程编译的内核版本是2.6.10，这中间内核本身已经发生了翻天覆地的变化。说白了，能make过去，那才出鬼了，好吧，一个错误一个错误来，不急。
直接make，第一个问题来了。。。。
根据提示把Makefile里的CFLAGS 改成EXTRA_CFLAGS 即可，继续……
提示：
如果您使用的是vi，可以和我一样一道命令解决:0,$s/CFLAGS/EXTRA_CFLAGS/g
别忘了保存，继续make……
第二个问题来了。。。。
好吧，我不理解了，讲驱动最常见的ioctl 你不认识，why？
原来在2.6.36版本更新中，file_operations发生了很大的变化，去掉了ioctl，而加入了两个新函数
long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long); long (*compat_ioctl) (struct file *, unsigned int, unsigned long);
注：2.6.38的file_operation结构体
struct file_operations { struct module *owner; loff_t (*llseek) (struct file *, loff_t, int); ssize_t (*read) (struct file *, char __user *, size_t, loff_t *); ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *); ssize_t (*aio_read) (struct kiocb *, const struct iovec *, unsigned long, loff_t); ssize_t (*aio_write) (struct kiocb *, const struct iovec *, unsigned long, loff_t); int (*readdir) (struct file *, void *, filldir_t); unsigned int (*poll) (struct file *, struct poll_table_struct *); long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long); long (*compat_ioctl) (struct file *, unsigned int, unsigned long); int (*mmap) (struct file *, struct vm_area_struct *); int (*open) (struct inode *, struct file *); int (*flush) (struct file *, fl_owner_t id); int (*release) (struct inode *, struct file *); int (*fsync) (struct file *, int datasync); int (*aio_fsync) (struct kiocb *, int datasync); int (*fasync) (int, struct file *, int); int (*lock) (struct file *, int, struct file_lock *); ssize_t (*sendpage) (struct file *, struct page *, int, size_t, loff_t *, int); unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long); int (*check_flags)(int); int (*flock) (struct file *, int, struct file_lock *); ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, loff_t *, size_t, unsigned int); ssize_t (*splice_read)(struct file *, loff_t *, struct pipe_inode_info *, size_t, unsigned int); int (*setlease)(struct file *, long, struct file_lock **); long (*fallocate)(struct file *file, int mode, loff_t offset, loff_t len); };
问题找到了，那么怎么解决呢？在main.c 文件中：
按照我下面的代码这样改就OK了。
* The unlocked_ioctl() implementation */ int scull_unlocked_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
还有在file_operation 赋值处修改如下：
struct file_operations scull_fops = { .owner = THIS_MODULE, .llseek = scull_llseek, .read = scull_read, .write = scull_write, .unlocked_ioctl = scull_unlocked_ioctl, .open = scull_open, .release = scull_release, };
在pipe.c 和scull.h 以及access.h 中也类似修改。
再次make，至少这个问题已经解决了，但是新的问题又来了……
第三个问题来了。。。。
把init_MUTEX(&scull_devices[i].sem); 修改为sema_init(&scull_devices[i].sem, 1);
在access.c 文件中做相似修改。
第四个问题来了。。。。
在pipe.c 中添加一个头文件：#include <linux/sched.h>
第五个问题来了。。。。
在access.c 中添加一个头文件：#include <linux/sched.h>
第六个问题来了。。。。
truct task_struct定义在include/linux/sched.h中，原来task_struct结构体定义有所改动，将uid和euid等挪到cred中，见include/linux/sched.h和include/linux/cred.h。
因此只需要将报error的代码做如下修改
current->uid 修改为 current->cred->uid
current->euid 修改为 current->cred->euid
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OK，make成功！！！！！！！！！！！！！
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