IO(1) IO(1)
NAME
io - access PC I/O registers
SYNOPSIS
io [ -f file ] [ -WLME ] [ -r | -w ] address [ value ] [
mask ]
DESCRIPTION
io accesses PC I/O space. The operation to be performed is
selected with -r or -w for reading or writing, respectively.
When a mask is provided for a read, it is applied with a
logical AND operation to the value. When a mask is provided
for a write, the set bits in the mask select the bits from
value to be modified. The default operation size is a byte.
C style notation for integers (e.g. 0x42 or 023) is
accepted for the address, value and mask parameters.
-W Perform a word (16 bit) operation.
-L Perform a long / double word (32 bit) operation.
-M Access a 64 bit wide machine specific register (MSR).
-E Access embedded controller space.
-f Instead of using /dev/io* as the I/O file depending on
the options above, use the argument file instead. This
can be used, for example, to access some PCI card con-
fig space by specifying /dev/pci/*raw as the I/O file.
SOURCE
/sys/src/cmd/io.c
SEE ALSO
seg(1), arch(3)
HISTORY
Io first appeared in 9front (April, 2011).
Page 1 Plan 9 (printed 7/3/25)