IBM RS/6000 - Manual (Page 100)

This list cannot be changed. The second is a customized list, and it can be
changed by using the
bootlist command or by using System Management
Services (SMS - see 4.6, “System Management Service (SMS)” on page 72).
When AIX is installed, it will set the customized list using the
bootlist command so
that the hard disk which has been installed will boot when the RS/6000 is powered
on.
Figure 26 shows the menu in SMS which is used to change the customized Boot
List.
Figure 26. Boot Sequence Selection Submenu
On all RS/6000 machines, the key position, either physical or electronic, determines
the way in which the RS/6000 will boot. On the microchannel-based RS/6000
systems, the position of the key at boot time will determine which Boot List to use.
With these machines, there are two customized Boot Lists: one for Normal and one
for Service. Typically, the Normal Boot List would contain an entry to try and boot
from hard disk first, and the Service Boot List would contain the diskette first
followed by the tape drive, CD-ROM and hard disk.
AIX will also react differently depending on the position of the key. Booting AIX
(from hard disk) with the key in the Normal position will result in the operating
system booting normally and users being able to log onto the system. Booting AIX
(from the hard disk) with the key in Service position will result in the operating
system loading diagnostics so that the administrator can test hardware components
of the system and check the AIX error logs.
The 40P was the first RS/6000 to be provided without a physical key. Instead, the
machine was permanently set to Normal mode. As with the 40P, the 43P only
operates in Normal mode due to the absence of an electronic or physical key. The
system key-switch abstraction exists, but no electronic or physical key exists on the
platform. No initial state is communicated from the firmware to AIX, and the system
key-switch remains in the Normal position. This means that when AIX boots, it can
only see the key in Normal mode.
76 Introduction to PCI-Based RS/6000 Servers