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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 3.22 of the Linux man-pages project.  A description of the project, and informa-
       tion about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



Linux                             1995-11-29                           OUTB(2)