1OUTB(2) Linux Programmer's Manual OUTB(2)
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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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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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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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34 ioperm(2), iopl(2)
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38Linux 1995-11-29 OUTB(2)