Man Linux: Main Page and Category List


       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


       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)


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