Solaris basics: booting process on SPARC systems

SPARC systems rely on OpenBoot (IEEE-1275).
The environment behind is a configurable and programmable session run by the OpenBoot PROM (OPB).

The OPB utility sets up a SPARC system to accept and execute the kernel.
The boot process reduces to four phases:

  1. OpenBoot PROM
  2. Booter
  3. Ramdisk
  4. Kernel

The OpenBoot PROM starts by looking for a file system reader.
If you’re booting from a disk, you first need its layout. The boot disk stores a partition map (VTOC) at sector 0.
OBP will find and load a file reader from sector 1-15 (boot block), then it can find and read the boot archive, a collection of configuration files and drivers.

The boot utility will pass the OPB environment variables to the kernel.
By calling boot -a, you can invoke an interactive session to override the values passed as defaults.

boot -m will override the default running state or logging level:

boot -m milestone=<milestone>

Values for milestones are:

  • none (point where you can repair the services facility)
  • all
  • single-user
  • multi-user
  • multi-user-server

The second option for boot -m is:

boot -m [quiet | verbose | debug]

reboot -f will apply the Fast Reboot feature (default on x86 but not on SPARC).