outb, outw, outl, outsb, outsw, outsl - port output
inb, inw, inl, insb, insw, insl - port input
outb_p, outw_p, outl_p, inb_p, inw_p, inl_p - paused I/O
This family of functions is used to do low level port input and output.
They are primarily designed for internal kernel use, but can be used
from user space, given the following information in addition to that
given in outb(9)
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.
outb and friends are hardware specific. The port and value arguments
are in the opposite order to most DOS implementations.
Linux 1995-11-29 OUTB(2)
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