Kernel
Linux Kernel Related
Kernel参数相关定义
fastcall是在include/asm-i386/linkage.h中定义的宏，它指导 GCC连接时把fastcall修饰的函数的前三个参数用寄存器传递。另外一个类似的宏asmlinkage则告诉GCC不要用寄存器传递参数， asmlinkage和fastcall不能共存。
copy on write
Franky, one cannot predict which pages will get copied on
write since that is related to the behaviour of the process:
if the process writes, then the corresponding page gets copied.
If the vma has the VM_WRITE flag set, and the pte is read-only,
the page is a candidate to become subject to copy on write.
问题是，我如何将一块用户级别的缓存配置为Copy on write,需要设置什么操作之类的东西？
需要通过测试比较代价，但是由于共享内存的消息接收方的操作基本上都是读操作不会出现过多的写操作，估计是可行的，
需要研读内核代码进行分析。
struct list_head {
struct list_head *next, *prev;
};
list_head结构用于构造双向环形链表
LIST_HEAD(head) : 定义一个空表头
struct list_head head = {&head,&head};
INIT_LIST_HEAD(head) : 初始化一个已定义的表头;
head->next = head;
head->prev = head;
list_add(entry,head); 将entry添加到head之后,用于构造堆栈
head->next->prev = entry;
entry->next = head->next;
entry->prev = head;
head->next = entry;
list_add_tail(entry,head) : 将entry添加到head之前,用于构造队列
head->prev = entry;
entry->next = head;
entry->prev = head->prev;
head->prev->next = entry;
list_del(entry) : 删除entry
entry->next->prev = entry->prev;
entry->prev->next = entry->next;
list_del_init(entry) : 删除并复位entry
entry->next->prev = entry->prev;
entry->prev->next = entry->next;
entry->next = entry;
entry->prev = entry;
list_empty(head) : 测试环形链表是否为空
(head->next == head)
list_splice(list,head) : 将两个环形链表合成一个大表
list->prev->next = head->next;
list->next->prev = head;
head->next->prev = list->prev;
head->next = list->next;
list_entry(ptr,type,member) :
如果type结构中member的地址是ptr,则返回type结构的地址
((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
list_for_each(entry,head) : 遍历链表
for (entry = (head)->next; entry != (head); entry = entry->next)