| NAME | DESCRIPTION | CONFORMING TO | SEE ALSO | COLOPHON | The Linux Programming Interface |
OUTB(2) Linux Programmer's Manual OUTB(2)
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
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.
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.
ioperm(2), iopl(2)
This page is part of release 3.32 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)
HTML rendering created 2010-12-03 by Michael Kerrisk, author of The Linux Programming Interface