HPUX boot process explained. Learn which all processes happened in the background while HPUX server boots.

It’s not a fully detailed boot process. It’s a very short form of things happens during boot. To make it understand and remember (for interviews) easily!

1) PDC (processor dependent code) gets executed

• Checks CPU
• Checks stable storage for the boot path
• Loads ISL utilities from leaf area of the boot disk
• Here you can halt boot using ESC key and can run PO, SEA commands.

2) ISL (Initial system loader) gets loaded

• Read AUTO file default kernel
• Load and runs HPUX from LIF area
• Here you can halt the boot process and boot system into single-user mode. You can provide diff options to SSL i.e. kernel vmunix. Like,hpux –ishpux –lq, hpux –lm

3) HPUX loads (Secondary system loader)

• Uses options and path names from ISL to load the kernel
• And by default loads vmunix

4) After kernel vmunix gets loaded –

• Swapper daemon starts with PID 0
• Kernel runs /sbin/pre_init_rc
• Kernel calls /sbin/init
• /sbin/init reads /etc/inittab and calls –

1. /sbin/ioinit – to scan hardware and build kernel io tree
2. /sbin/bcheckrc – to check FS listed in /etc/fstab
3. /sbin/rc – to start additional services like lp, cron, cde
4. /usr/sbin/getty – to start n show login prompt to the user.

Please note that this is not the exact hpux boot process. There are alterations depends on the system being referred to is PA-RISC or Itanium. This article gives a fair idea of what’s happening in the background when HPUX boot happens.