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.

bootblk loads ufsboot, the secondary boot program.

ufsboot reads the /etc/bootrc script, which loads the kernel.

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.