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* func-
       tions 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  with-
       out 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 3.25 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)