dnl	$OpenBSD: prep,v 1.9 2006/06/26 21:11:11 dlg Exp $
Before you install your system, you should familiarize yourself with the
ARCS setup and how to run programs from the Command monitor prompt.

Accessing the Maintenance Console:

    When the system starts up, press the ESC key or use the mouse and
    click the ``stop for maintenance'' button. Once in the System
    Maintenance Menu, select '5' (or click the appropriate icon if you
    are using the graphics console) to go into the Command Monitor.

    If the internal disk with the lowest SCSI ID does not contain a
    valid Volume Header, but is bootable, the Maintenance Console will
    be entered by default.

    The first time the Maintenance Console is entered, it may be
    necessary to force a reset of the environment to its default
    settings by entering the ``resetenv'' command at the chevron
    prompt. If some variables have been set explicitly, this may
    disturb the normal OpenBSD boot process.

Switching from serial to graphics console and vice versa:

    Booting the ramdisk kernel can be done from the ARCS graphic console
    although it might be more convenient to use the serial console since
    the kernel currently only supports the serial console. Some systems
    come with the serial console enabled by default but sometimes
    this must be changed.

    To change to serial console, go into the ARCS Maintenance Console
    and change the ``console'' environment variable, and power-cycle
    the machine.

    > setenv console d

    will select 9600 8N1, no flow control, serial console on the first
    serial port (labeled ``(1)''), while

    > setenv console g

    will select the graphics console.

Setting the environment:

    When setting up the system to boot from disk, the ``OSLoader''
    environment variable will need to be changed.

    Its default value is ``sash'', which is IRIX' standalone
    shell and loader. Set it to ``boot'', the OpenBSD boot loader.

Disk numbering

    SGI numbers their disks 1-n depending on their position in the
    backplane. For example, on the O2, the slot closest to the CPU
    is numbered 1 and the next 2 if the CPU is a R5000. On R1x000
    models, slot 1 is lost due to the larger heatsink on the CPU.
    Normally the kernel translates the slot numbers to disk numbers
    by subtracting 1 from the slot number, eg slot 1 becomes sd0.
    However on an O2 with a R1x000 cpu, 2 is subtracted from the
    slot number to compensate for the lost slot.

    When the kernel searches for the boot device it uses the ARCBios
    environment variable OSLoadPartition. Since the disk number in
    the variable is the absolute number, in contrast to the kernels
    relative numbers, the kernel will not be able to find the boot
    device if the disk slots are not filled from the lowest and up.
    An empty slot before the boot device will confuse the lookup.