[SunHELP] Boot Process Phases

TAMTONAX abdulrashed.tamton at aramco.com
Tue Apr 18 00:03:45 CDT 2006

I do not know what exactly you mean; but this one should be pretty same for
all Solaris but a the info is bit old.

Boot Sequence

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. (See the
Hardware Diagnostics page for more information on these settings.) 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 VxVM or DiskSuite.
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

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

/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
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.

Rasheed Tamton

-----Original Message-----
From: sunhelp-bounces at sunhelp.org [mailto:sunhelp-bounces at sunhelp.org] On
Behalf Of Abrar, Saaim M.
Sent: Tuesday, April 18, 2006 8:00 AM
To: sunhelp at sunhelp.org
Subject: [SunHELP] Boot Process Phases

Hi Gurus,
What is the correct order of Boot Processes for Sparc Based System ?
Many Regards

Saaim Abrar
System Engineer
Jeraisy Computers and Communications
Oracle Certified 10G Professional
Database Administrator

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