How Devices Are Detected And Numbered; How To Use The Hardware Graph - Silicon Graphics Origin200 Owner's Manual

Chapter 4: Operating an Origin200 System
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How Devices Are Detected and Numbered

When the system boots, it probes all of the attached hardware. As it enters multiuser
mode, it runs the ioconfig utility, which examines the /hw filesystem (described in the next
section, "How to Use the Hardware Graph") to assign unique controller numbers for
each device it finds. The results of this process are stored in the file /etc/ioconfig.conf,
which maps logical controller numbers to device names.
Be aware of the following:
• When the system boots and probes hardware, there is no guarantee that it will
detect devices in a particular order (except for certain fixed devices in the master
module, such as the console serial port, SCSI controllers 0 and 1, and the primary
Ethernet port).
• When you remove devices from the system, the logical controller numbers are not
automatically removed from /etc/ioconfig.conf.
You can change the way that devices are numbered by editing the file /etc/ioconfig.conf.
See ioconfig(1M) for more information.

How to Use the Hardware Graph

The hardware graph is a tool for inventorying the I/O devices on all Silicon Graphics
Origin and Onyx2 systems. Unlike hinv, the hardware graph is an IRIX filesystem, whose
branching character accommodates the possibility of multiple nodes, each with multiple
I/O devices of several types. The hardware graph keeps track of information in the
kernel that is associated with the hardware.
Most of the hardware graph directories are much like their /dev counterparts, but module
numbers are persistent across reboots and hardware changes (until you change the
module numbers).