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

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

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

34       ioperm(2), iopl(2)
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38Linux                             1995-11-29                           OUTB(2)
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