Re: Direct I/O reads/writes from C programs

[ellis]

In article <>,
Dave  <[EMAIL PROTECTED]> wrote:

>How does one directly access an I/O address from C?

>From linux user space?

>For example if I want to write a char to port 0x80 (or read a char from a
>port) what is the statement? 

outb(c,0x80);  Writes the value in c to port 0x80.  You have to have
called iopl (see man iopl) as root to set permissions first.  Definitions
for the io calls are in #include <asm/io.h>.  Typing "man outb" should
get you more information.