Solaris SPARC Boot Sequence

This article provides a summary of the boot process for a SPARC system running the Solaris 2.x operating system.

Power On: Depending on the system involved, you may see some output on a serial terminal immediately after power on. This may take the form of a Hardware Power ON message on a large Enterprise server, or a "'" or "," in the case of an older Ultra system. These indications will not be present on a monitor connected directly to the server.

POST: If the PROM diag-switch? parameter is set to true, output from the POST (Power On Self Test) will be viewable on a serial terminal. The PROM diag-level parameter determines the extent of the POST tests. If a serial terminal is not connected, a prtdiag -v will show the results of the POST once the system has booted. If a keyboard is connected, it will beep and the keyboard lights will flash during POST. If the POST fails, an error indication may be displayed following the failure.

Init System: The "Init System" process can be broken down into several discrete parts:

OBP: If diag-switch? is set, an Entering OBP message will be seen on a serial terminal. The MMU (memory management unit) is enabled.

NVRAM: If use-nvramrc? is set to true, read the NVRAMRC. This may contain information about boot devices, especially where the boot disk has been encapsulated with Solstice DiskSuite or Veritas Volume Manager.

Probe All: This includes checking for SCSI or other disk drives and devices.

Install Console: At this point, a directly connected monitor and keyboard will become active, or the serial port will become the system console access. If a keyboard is connected to the system, the lights will flash again during this step.

Banner: The PROM banner will be displayed. This banner includes a logo, system type, PROM revision level, the ethernet address, and the hostid.

Create Device Tree: The hardware device tree will be built. This device tree can be explored using PROM monitor commands at the ok> prompt, or by using prtconf once the system has been booted.

Extended Diagnostics: If diag-switch? and diag-level are set, additional diagnostics will appear on the system console. auto-boot?: If the auto-boot? PROM parameter is set, the boot process will begin. Otherwise, the system will drop to the ok> PROM monitor prompt, or (if sunmon-compat? and security-mode are set) the > security prompt. The boot process will use the boot-device and boot-file PROM parameters unless diag-switch? is set. In this case, the boot process will use the diag-device and diag-file.

bootblk: The OBP (Open Boot PROM) program loads the bootblk primary boot program from the boot-device (or diag-device, if diag-switch? is set). If the bootblk is not present or needs to be regenerated, it can be installed by running the installboot command after booting from a CDROM or the network. A copy of the bootblk is available at /usr/platform/`arch -k`/lib/fs/ufs/bootblk

ufsboot: The secondary boot program, /platform/`arch -k`/ufsboot is run. This program loads the kernel core image files. If this file is corrupted or missing, a bootblk: can't find the boot program or similar error message will be returned.

kernel: The kernel is loaded and run.

  • For 32-bit Solaris systems, the relevant files are:
    /platform/`arch -k`/kernel/unix
  • For 64-bit Solaris systems, the files are:
    /platform/`arch -k`/kernel/sparcV9/unix

As part of the kernel loading process, the kernel banner is displayed to the screen. This includes the kernel version number (including patch level, if appropriate) and the copyright notice.

The kernel initializes itself and begins loading modules, reading the files with the ufsboot program until it has loaded enough modules to mount the root filesystem itself. At that point, ufsboot is unmapped and the kernel uses its own drivers. If the system complains about not being able to write to the root filesystem, it is stuck in this part of the boot process.

The boot -a command singlesteps through this portion of the boot process. This can be a useful diagnostic procedure if the kernel is not loading properly.

/etc/system: The /etc/system file is read by the kernel, and the system parameters are set. The following types of customization are available in the /etc/system file:

  • moddir: Changes path of kernel modules.
  • forceload: Forces loading of a kernel module.
  • exclude: Excludes a particular kernel module.
  • rootfs: Specify the system type for the root file system. (ufs is the default.)
  • rootdev: Specify the physical device path for root.
  • set: Set the value of a tuneable system parameter.

If the /etc/system file is edited, it is strongly recommended that a copy of the working file be made to a well-known location. In the event that the new /etc/system file renders the system unbootable, it might be possible to bring the system up with a boot -a command that specifies the old file. If this has not been done, the system may need to be booted from CD or network so that the file can be mounted and edited.

kernel initialized: The kernel creates PID 0 ( sched). The sched process is sometimes called the "swapper." init: The kernel starts PID 1 (init). init: The init process reads the /etc/inittab and /etc/default/init and follows the instructions in those files. Some of the entries in the /etc/inittab are: fs: sysinit (usually /etc/rcS) is: default init level (usually 3, sometimes 2) s#: script associated with a run level (usually /sbin/rc#)

rc scripts: The rc scripts execute the files in the /etc/rc#.d directories. They are run by the /sbin/rc# scripts, each of which corresponds to a run level. Debugging can often be done on these scripts by adding echo lines to a script to print either a "I got this far" message or to print out the value of a problematic variable.