io

Documentation

Overview

io reads and writes to physical memory and ports.

Synopsis:

io (r{b,w,l,q} address)...
io (w{b,w,l,q} address value)...
# x86 only:
io (in{b,w,l} address)
io (out{b,w,l} address value)
io (cr index}
io {cw index value}...

Description:

io lets you read/write 1/2/4/8-bytes to memory with the {r,w}{b,w,l,q}
commands respectively.

On x86 platforms, {in,out}{b,w,l} allow for port io.

Use cr / cw to write to cmos registers

Examples:

# Read 8-bytes from address 0x10000 and 0x10000
io rq 0x10000 rq 0x10008
# Write to the serial port on x86
io outb 0x3f8 50

The System Management Network (SMN, try to say it fast) is a parallel universe address space on newer AMD64 cpus. The address is 32 bits, as is data. Unfortunately it is only accessible via the classic index/register pair. Fortunately that pair is accessible in mmconfig space.