5.5.3. - Enabling I/O Ports On PC Platforms (not linux)
The spec distribution includes a program called
io_enable
for use on
systems derived from
AT&T System V/386 UNIX.
This program
enables user programs (such as spec) to write to selected
I/O ports on the adapter cards plugged into the motherboard.
spec automatically invokes
io_enable
if the hardware configuration requires it.
Ports only need to be enabled once after booting the computer.
The total number of ports that can be enabled is quite limited, though.
The
io_enable
program must be owned by root and have
set-user-id execute mode.
You can invoke
io_enable
from the shell using the following syntax:
io_enable [-d] port_address [port_address ...]
The
-d option causes the specified ports to be removed from the systems list
of enabled ports.
Port addresses must be given as hexadecimal numbers with a
0x prefix.
The addresses may be specified either individually,
as a hyphen-separated range, or as a base address followed by a comma and
a count.
Usage might be,
io_enable 0x300-0x302 0x312,4
to add 0x300, 0x301, 0x302, 0x312, 0x313, 0x314 and 0x315 to the
enabled-port list.
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