先寫下LDD3P59頁字符設備的註冊一節的原文：
我們前面提到，內核內部使用struct cdev結構來表示字符設備。。。
分配和初始化上述結構的方式有兩種。如果讀者打算在運行時獲取一個獨立的cdev結構，則應該如下編寫代碼：
struct cdev *my_cdev = cdev_alloc();
my_cdev->ops = &my_fops;
這時，你可以將cdev結構嵌入到自己的設備待定結構中，scull就是這樣做的。這種情況下，我們需要用下面的代碼來初始化已分配到的結果：
void cdev_init(struct cdev *cdev, struct file_operations *fops);
。。。
上面是部分原文，主要是”這時“讓我產生了誤解，以爲是上面申請好後，下面進行了初始化。
查看了英文的原文：（多copy了兩段）
There are two ways of allocating and initializing one of these structures. If you wish to obtain a standalone cdev structure at runtime, you may do so with code such as:
struct cdev *my_cdev = cdev_alloc( );
my_cdev->ops = &my_fops;
Chances are, however, that you will want to embed the cdev structure within a device-specific structure of your own; that is what scull does. In that case, you
should initialize the structure that you have already allocated with:
void cdev_init(struct cdev *cdev, struct file_operations *fops);
Either way, there is one other struct cdev field that you need to initialize. Like the file_operations structure, struct cdev has an owner field that should be set to
THIS_MODULE.
Once the cdev structure is set up, the final step is to tell the kernel about it with a call to:
int cdev_add(struct cdev *dev, dev_t num, unsigned int count);
找到了有疑問的那一段，查了下解釋：
chances are that：可能
initialize： vt 初始化
它的意思是指你可以在運行時動態的分配一個cdev結構，也可以把cdev結構內嵌到一個自己的設備結構中然而後者就需要使用cdev_init來初始化你已分配的結構。
所以
struct cdev *my_cdev = cdev_alloc();
my_cdev->ops = &my_fops;
和
void cdev_init(struct cdev *cdev, struct file_operations *fops);
是對cdev結構的兩種初始化方式。