1OUTB(2)                    Linux Programmer's Manual                   OUTB(2)
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NAME

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

10       This family of functions is used to do low-level port input and output.
11       The out* functions do port output, the in* functions do port input; the
12       b-suffix functions are byte-width  and  the  w-suffix  functions  word-
13       width; the _p-suffix functions pause until the I/O completes.
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15       They  are  primarily  designed for internal kernel use, but can be used
16       from user space.
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18       You compile with -O or -O2 or similar.  The functions  are  defined  as
19       inline  macros,  and  will  not  be substituted in without optimization
20       enabled, causing unresolved references at link time.
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22       You use ioperm(2) or alternatively iopl(2) to tell the kernel to  allow
23       the  user space application to access the I/O ports in question.  Fail‐
24       ure to do this will cause the application  to  receive  a  segmentation
25       fault.
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CONFORMING TO

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

33       ioperm(2), iopl(2)
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COLOPHON

36       This  page  is  part of release 3.25 of the Linux man-pages project.  A
37       description of the project, and information about reporting  bugs,  can
38       be found at http://www.kernel.org/doc/man-pages/.
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42Linux                             1995-11-29                           OUTB(2)