1 I/O port access from the command line
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5 This package adds commands to access machine I/O ports directly. For
11 Note most of the time you should never use these commands unless you
12 know what you are doing.
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17 The commands are pretty much used as you would expect. For additional
18 help, use '--help' and/or read the manual page.
20 You will need to run the commands as root. Strictly speaking you will
21 need CAP_SYS_RAWIO capability.
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26 At first glance it would seem that /dev/port would be the best way to
27 access I/O ports. However /dev/port under Linux is fundamentally
28 flawed because it only allows byte-sized access to ports. For example
29 if you write a single long (4 bytes) it will turn that into 4
30 individual outb operations.
32 Instead we use iopl(2) to raise our I/O privilege level so that we can
33 do the correct in<size> and out<size> operation as requested.