看驱动的时候，时常会有如下代码：

.remove = __devexit_p(XX_exit),

这里的__devexit_p有什么作用呢？

我在include/linux/init.h中找到了它的定义：

/* Functions marked as __devexit may be discarded at kernel link time, depending

on config options. Newer versions of binutils detect references from

retained sections to discarded sections and flag an error. Pointers to

__devexit functions must use __devexit_p(function_name), the wrapper will

insert either the function_name or NULL, depending on the config options.

*/

#if defined(MODULE) || defined(CONFIG_HOTPLUG)

#define __devexit_p(x) x

#else

#define __devexit_p(x) NULL

#endif

 

编译成模块或有热拔插功能时， 就需要exit函数。 否则可以为NULL， 节约空间