Solaris Boot Process

The Solaris 10 OS boot process :
There are five phases, a Solaris box passes through during the boot process:
1. Boot PROM phase

This is the first phase during the boot process. As soon as a Solaris box is booted, it is controlled by the software coming from the PROM chip. This PROM software (BIOS on Intel arch. is almost a similar idea) performs the POST (Power On Self Test) and then allows the user to interact through the "ok" prompt  offered by it. PROM invokes "boot" command whether specified interactively or automatically for a reboot.

Amongst several other variables, two NVRAM variables are of importance during the boot process - "boot-device", which informs the boot command as to where to find the next stage i.e. bootblk program to continue further. Typical values of boot-device variable may include - disk, disk0 disk1, mirrordisk, net etc. These values are alias to actual device paths which can be listed using devalias, show-devs, show-disks etc. Another variable is "auto-boot?" - which is a variable that can only hold true or false. True value ensures that it boots with the default boot-device values instead of waiting for a user input at "ok" prompt.

2. Boot Program phase

3. Kernel Initialization

4. init phase

5. svc.startd phase