OUTB(2) 						     Linux Programmer's Manual							   OUTB(2)

NAME

       outb, outw, outl, outsb, outsw, outsl, inb, inw, inl, insb, insw, insl, outb_p, outw_p, outl_p, inb_p, inw_p, inl_p - port I/O

DESCRIPTION

       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.

       They are primarily designed for internal kernel use, but can be used from user space.

       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.

CONFORMING TO

       outb() and friends are hardware-specific.  The value argument is passed first and the port argument is passed second, which is the opposite
       order from most DOS implementations.

SEE ALSO

       ioperm(2), iopl(2)

COLOPHON

       This  page is part of release 3.27 of the Linux man-pages project.  A description of the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.

Linux								    1995-11-29								   OUTB(2)