16.4 Booting from the Old Kernel | HP Certified: HP-UX System Administration

Sometimes you are not able to boot the system with the newly created kernel. In that case, you need to interact with the initial system loader (ISL). ISL calls a utility called hpux , which is used to load the HP-UX kernel. By default, it loads the /stand/vmunix kernel unless otherwise specified.

In case of a bad kernel, restart the system and wait for the following message.

 Processor is starting the autoboot process. To discontinue press a key within 10 seconds.

As soon as this message appears, press a key to enter the processor dependent code (PDC) menu. At the PDC command prompt, enter the boot command to start the boot process from the primary boot device. Your system will ask you if you want to interact with the ISL. Answer "yes" and you will get the ISL prompt. This process looks like the following.

 ---------------------- Main Menu -------------------------- Command                       Description -------                       ----------- BOot [PRIALT<path>]         Boot from specified path PAth [PRIALT<path>]         Display or modify a path SEArch [DisplayIPL] [<path>] Search for boot device COnfiguration menu            Displays or sets boot values INformation menu              Displays hardware information SERvice menu                  Displays service commands Help [<menu><command>]       Displays help for menu or cmd RESET                         Restart the system ---------- Main Menu: Enter command or menu >  boot pri  Interact with ISL (Y or N) ?>  Y  ISL>

Now, at the ISL prompt use the hpux command to boot from the old kernel.

 ISL>  hpux /stand/vmunix.old

The system will boot with vmunix.old instead of vmunix . After reboot, you can restore the old kernel or make changes to correct the problems with the new kernel.

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