x86: The Boot Process

BIOS Phase 

The PC BIOS loads and executes any hardware device's BIOS. 

The BIOS boot program loads and executes the master boot record, mboot.

Boot Programs Phase 

mboot loads pboot, the Solaris boot partition, boot program.

pboot loads bootblk, the primary boot program.

bootblk reads the fdisk table to locate the default boot partition. The Primary Boot Subsystem menu is displayed at this time.

bootblk loads the secondary boot program, boot.bin or ufsboot. You can press the ESC key to enter the Configuration Assistant Menu at this point.

The secondary boot program, boot.bin or ufsboot, reads the /etc/bootrc script, which loads the kernel. The Solaris Boot options menu is displayed at this time.

Kernel Initialization Phase 

The kernel initializes itself and loads the modules needed to mount the root (/) file system.

The kernel starts the init process.

init Phase

The init process starts the run control scripts.