Managing Systems and Workgroups: A Guide for HP-UX System Administrators

Configuring a System
Reconfiguring the Kernel (HP-UX 11i Version 2)
Chapter 3366
If you want to disable the automatic replacement of the backup
configuration for a particular change, specify -K. If you want to force an
automatic replacement of the backup configuration, specify -B (Backup).
These options work with any kernel configuration command that makes
configuration changes.
Booting a Saved Configuration
In extreme circumstances, a mistaken configuration change can result in
a kernel configuration that won’t boot. In these cases, you have two
options: boot a different configuration, such as the automatic backup
configuration, and/or boot in fail-safe mode (described below).
To boot a saved configuration on an Itanium-based system, interrupt the
automatic boot process when it reaches the point that it has started the
HP-UX boot loader. (On most systems, this is during the second
10-second countdown.) At the HPUX> prompt, type
HPUX> boot configname
To boot a saved configuration on a PA-RISC system, interrupt the
automatic boot process when you arrive at the boot console handler. Tell
it to boot from the desired device (typically with a boot pri command).
When it asks if you want to interact with the ISL or IPL, say Yes. (The
exact mechanism to get to this point varies; consult your system’s
hardware manual or the hpux (1M) manpage for details.) At the ISL>
prompt, type
ISL> hpux configname/vmunix
In either case, this will boot the saved configuration named configname.
When the boot is complete, it will be the currently running configuration;
the previous configuration is lost (unless it had been automatically saved
as backup).
Booting in Fail-Safe Mode
The other alternative for recovering from an unbootable configuration is
booting in fail-safe mode. When you boot the system in fail-safe mode,
your configuration settings are ignored. All kernel tunables are given
fail-safe values, default device bindings are used, and no kernel modules
are dynamically loaded during boot. This method is particularly useful
when a hardware change or failure has caused all of your saved
configurations to be unbootable.