SPARC: The Boot Process Details

Boot PROM 

1. The PROM displays system identification information and then runs self-test diagnostics to verify the system's hardware and memory. 

2. Then the PROM loads the primary boot program, bootblk, whose purpose is to load the secondary boot program located in the ufs file system from the default boot device.

Boot Programs 

3. The bootblk program finds and executes the secondary boot program, ufsboot, and loads it into memory.

4. After ufsboot program is loaded, the ufsboot program loads the kernel.

Kernel Initialization 

5. The kernel initializes itself and begins loading modules, using ufsboot to read the files. When the kernel has loaded enough modules to mount the root file system, it unmaps the ufsboot program and continues, using its own resources.

6. The kernel creates a user process and starts the /sbin/init process, which starts other processes by reading the /etc/inittab file.

init

7. The /sbin/init process starts the run control (rc) scripts, which execute a series of other scripts. These scripts (/sbin/rc*) check and mount file systems, start various processes, and perform system maintenance tasks.