Navigating the PROM Hardware Tree
For versions 2.x and higher (SparcStation 2 and newer),
the OpenBoot firmware provides for two command line interfaces:
- Restricted Monitor: This interface is signalled by the
> prompt. It provides for execution of the b
(boot), c (continue), and n (new command mode) commands.
The Restricted Monitor is used to implement PROM security via the
- PROM Monitor: (Also known as the "Forth Monitor" or the
"New Monitor.") This interface provides additional control, including
a Forth command interpreter. The PROM Monitor is signalled by the
Once in the
ok> PROM monitor mode, it is possible to examine
the tree of hardware devices known by the system. The following are the
crucial commands to remember:
cd changes location in the device tree
ls lists the contents of the present node
pwd gives the current location in the device tree
dev device_pathname selects a particular node of
the tree for examination.
.properties shows the properties for a particular node.
device-end unselects a node.
The device names are cryptic, but are closely related to the names of
devices in the Operating System's
/etc/driver_aliases file may also be useful when
trying to identify a device.
A full device path node name has the following form:
One example of such a name represents the 0 slice of a sun4m boot disk:
The following commands may come in handy when trying to identify
the location of a device:
The ability to navigate the device tree on such a primitive level is
useful for troubleshooting. If the device in question is not present,
we have a physical connectivity issue. At that point, we might try
reset or power cycle, then check cables and terminators,
then examine the device itself.
If the device shows up on the PROM hardware tree but not in the Operating
System, we would try a
boot -r, examine the
/devices directories, and look at the relevant driver