描述
This family of functions is used to do low level port input and output. The out* functions do port output, the in* functions do port input; the b-suffix functions are byte-width and the w-suffix functions word-width; the _p-suffix functions pause until the I/O completes.它们主要被设计为内部内核使用，但也可以从用户空间使用。
You compile with -O or -O2 or similar. The functions are defined as inline macros, and will not be substituted in without optimization enabled, causing unresolved references at link time.
You use ioperm(2) or alternatively iopl(2) to tell the kernel to allow the user space application to access the I/O ports in question. Failure to do this will cause the application to receive a segmentation fault.
遵循于
outb() and friends are hardware specific. The value argument is passed first and the portargument is passed second, which is the opposite order from most DOS implementations.另请参阅
