System Administration Guide, Volume 1

Chapter 12 The Boot Process (Reference)

This chapter describes the hardware used for booting on SPARC based and IA based systems and a conceptual overview of the boot process on each platform.

This is a list of overview information in this chapter.

For instructions on booting a system, see Chapter 10, SPARC: Booting a System (Tasks) or Chapter 11, IA: Booting a System (Tasks).

SPARC: The Boot PROM

Each SPARC based system has a PROM (programmable read-only memory) chip with a program called the monitor. The monitor controls the operation of the system before the kernel is available. When a system is turned on, the monitor runs a quick self-test procedure that checks things such as the hardware and memory on the system. If no errors are found, the system begins the automatic boot process.

SPARC only -

Some older systems might require PROM upgrades before they will work with the Solaris system software. Contact your local service provider for more information.

SPARC: The Boot Process

The following table describes the boot process.

Table 12-1 SPARC: Description of the Boot Process


Boot Phase	Description
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 the `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.

IA: The PC BIOS

Before the kernel is started, the system is controlled by the read-only-memory (ROM) Basic Input/Output System (BIOS), the firmware interface on a PC.

Hardware adapters can have an onboard BIOS that displays the physical characteristics of the device and can be used to access the device.

During the startup sequence, the PC BIOS checks for the presence of any adapter BIOS, and if found, loads and executes each one. Each individual adapter's BIOS runs self-test diagnostics and displays device information.

IA: Boot Subsystems

At three times during the Solaris boot process, you can make the following choices about a booting system:

Primary Boot Subsystem (Partition Boot Menu) - This first menu appears if multiple operating environments exist on the disk. The menu enables you to boot any of the operating environments installed. By default, the operating environment designed as active is booted.

Note that if you choose to boot a non-Solaris operating environment, the next two menus cannot be reached.
Interrupt the Autoboot Process - If the autoboot process is interrupted, you can access the Configuration Assistant.

The Configuration Assistant enables you to boot the Solaris system from a different boot device, configure new or misconfigured hardware, or perform other device- or boot-related tasks.
Current Boot Parameters Menu - Two forms of this menu exist, one for a normal Solaris boot and one for a Solaris installation boot:
- The normal Current Boot Parameters menu enables you to boot the Solaris system with options, or enter the boot interpreter.
- The install Current Boot Parameters menu enables you to select the type of installation to be performed, or customize the boot.

The following table summarizes the purpose of the primary IA boot interfaces. See the sections that follow for a detailed description and example of each boot subsystem.

Table 12-2 IA: Boot Subsystems


Boot Subsystem	Purpose
Primary Boot Subsystem	This menu appears if the disk you are booting from contains multiple operating environments, including the Solaris operating environment.
Secondary Boot Subsystem	This menu appears each time you boot the Solaris release. The Solaris release is booted automatically unless you choose to run the Solaris Device Configuration Assistant by interrupting the autoboot process.
Solaris Device Configuration Assistant/Boot Diskette	There are two ways to access the Solaris Device Configuration Assistant menus: Use the Solaris Device Configuration Assistant Boot Diskette or the Solaris Installation CD (on systems that can boot from the CD-ROM drive) to boot the system. Interrupt the autoboot process when booting Solaris from an installed disk.
Current Boot Parameters Menu	This menu appears when you boot the Solaris release from the disk, CD-ROM, or the network. The menu presents a list of boot options.

During the boot process, the boot subsystem menus allow you to customize boot choices. If the system receives no response during the time-out periods, it continues to boot automatically using default selections. You can stop the boot process when each boot subsystem menu is displayed, or you can let it continue automatically.

The following section provides examples of each subsystem screen.

IA: Booting Solaris

During the device identification phase, the Configuration Assistant:

Scans for devices installed on the system
Displays the identified devices
Enables you to perform optional tasks such as selecting a keyboard type and editing devices and their resources

During the Boot phase, the Configuration Assistant:

Displays a list of devices from which to boot. A device marked with an asterisk (*) is the default boot device.
Enables you to perform optional tasks, such as editing autoboot and property settings, and choosing the network configuration strategy.

Examples of device identification during each phase are provided below. Device output varies based on your system configuration.

IA: Menus Displayed During the Device Identification Phase

Several menus are displayed as the Configuration Assistant attempts to identify devices on the system.

IA: Configuration Assistant Screen

This screen appears each time you boot the Configuration Assistant and access the menus. The Configuration Assistant runs every time the system is booted, although the autoboot process bypasses the menus.

Solaris Device Configuration Assistant

The Solaris(TM) (Intel Platform Edition) Device Configuration Assistant
scans to identify system hardware, lists identified devices, and can
boot the Solaris software from a specified device. This program must be
used to install the Solaris operating environment, add a driver,
or change the hardware on the system.
 
> To perform a full scan to identify all system hardware, choose Continue.
 
> To diagnose possible full scan failures, choose Specific Scan.
 
> To add new or updated device drivers, choose Add Driver.

About navigation...
    - The mouse cannot be used.
    - If the keyboard does not have function keys or they do not respond, 
      press ESC. The legend at the bottom of the screen will change to 
      show the ESC keys to use for navigation.
    - The F2 key performs the default action.
 
F2_Continue		F3_Specific Scan		F4_Add Driver		F6_Help

IA: Bus Enumeration Screen

The Bus Enumeration screen appears briefly while the Configuration Assistant gathers hardware configuration data for devices that can be detected automatically.

Bus Enumeration

Determining bus types and gathering hardware configuration data ...

Please wait ...

IA: Scanning Devices Screen

The Scanning Devices screen appears while the Configuration Assistant manually scans for devices that can only be detected with special drivers.

Scanning Devices

The system is being scanned to identify system hardware.

If the scanning stalls, press the system's reset button. When the
system reboots, choose Specific Scan or Help.


Scanning: Floppy disk controller

#######################
|      |        |         |         |         |
0	 		 20       40        60	       80       100

Please wait ...

IA: Identified Devices Screen

The Identified Devices screen displays which devices have been identified on the system. From here, you can continue to the Boot Solaris menu or perform optional tasks, such as set a keyboard configuration, view and edit devices, set up a serial console, and save and delete configurations.

Identified Devices

The following devices have been identified on this system. To identify
devices not on this list or to modify device characteristics, such as
keyboard configuration, choose Device Tasks. Platform types may be
included in this list.

ISA: Floppy disk controller
	ISA: Motherboard
	ISA: PnP bios: 16550-compatible serial controller
	ISA: PnP bios: 16550-compatible serial controller
	ISA: PnP bios: Mouse controller
	ISA: PnP bios: Parallel port
	ISA: System keyboard (US-English)
	PCI: Bus Mastering IDE controller
	PCI: Universal Serial Bus
	PCI: VGA compatible display adapter

F2_Continue   F3_Back   F4_Device Tasks   F6_Help

IA: Menus Displayed During the Boot Phase

During this phase, you can determine the way in which the system is booted.

IA: Boot Solaris Menu

The Boot Solaris menu allows you to select the device from which to boot the Solaris release. You can also perform optional tasks, such as view and edit autoboot and property settings. Once a boot device is selected and you choose Continue, the Solaris kernel will begin to boot.

Boot Solaris
Select one of the identified devices to boot the Solaris kernel and
choose Continue.

To perform optional features, such as modifying the autoboot and property
settings, choose Boot Tasks.

An asterisk (*) indicates the current default boot device.

> To make a selection use the arrow keys, and press Enter to mark it [X].

[X]  DISK: (*) Target 0:QUANTUM  FIREBALL1280A
on Bus Mastering IDE controller on Board PCI at Dev 7, Func 1
[ ]  DISK: Target 1:ST5660A
on Bus Mastering IDE controller on Board PCI at Dev 7, Func 1
[ ]  DISK: Target 0:Maxtor 9 0680D4
	on Bus Mastering IDE controller on Board PCI at Dev 7, Func 1
[ ]  CD  : Target 1:TOSHIBA  CD-ROM XM-5602B  1546
	on Bus Mastering IDE controller on Board PCI at Dev 7, Func 1

F2_Continue   F3_Back   F4_Boot Tasks   F6_Help

IA: Current Boot Parameters Menu

This menu appears each time you boot Solaris from the local disk. Let the five-second timeout elapse if you want to boot the default Solaris kernel. If you want to boot with different options, select an appropriate option before the timeout period elapses.

                     <<< Current Boot Parameters >>>
Boot path: /pci@0,0/pci-ide@7,1/ide@0/cmdk@0,0:a
Boot args: 
Type    b [file-name] [boot-flags] <ENTER>       to boot with options
or      i <ENTER>                                to enter boot interpreter
or      <ENTER>                                  to boot with defaults
 
 
                     <<< timeout in 5 seconds >>>
 
Select (b)oot or (i)nterpreter:

IA: The Boot Process

The following table describes the boot process.

Table 12-3 IA: Description of the Boot Process


Boot Phase	Description
BIOS	1. When the system is turned on, the PC BIOS runs self-test diagnostics to verify the system's hardware and memory. The system begins to boot automatically if no errors are found. If errors are found, error messages are displayed describing recovery options. Additional hardware devices' BIOS are run at this time.
	2. The BIOS boot program tries to read the first physical sector from the boot device. This first disk sector on the boot device contains the master boot record `mboot`, which is loaded and executed. If no `mboot` file is found, an error message is displayed.
Boot Programs	3. `mboot`, which contains disk information needed to find the active partition and the location of the Solaris boot program, `pboot`, loads and executes `pboot`.
	4. `pboot` loads `bootblk`, the primary boot program, whose purpose is to load the secondary boot program located in the `ufs` file system.
	5. If there is more than one bootable partition, `bootblk` reads the `fdisk` table to locate the default boot partition, and builds and displays a menu of available partitions. You have a 30-second interval to select an alternate partition from which to boot. This step only occurs if there is more than one bootable partition present on the system.
	6. `bootblk` finds and executes the secondary boot program, `boot.bin` or `ufsboot`, in the root file system. You have a 5-second interval to interrupt the autoboot to start the Configuration Assistant.
	7. The secondary boot program, `boot.bin` or `ufsboot`, starts a command interpreter that executes the `/etc/bootrc` script, which provides a menu of choices for booting the system. The default action is to load and execute the kernel. You have a 5-second interval to specify a boot option or start the boot interpreter.
Kernel Initialization	8. The kernel initializes itself and begins loading modules, using the secondary boot program (`boot.bin` or `ufsboot`) to read the files. When the kernel has loaded enough modules to mount the root file system, it unmaps the secondary boot program and continues, using its own resources.
	9. The kernel creates a user process and starts the `/sbin/init` process, which starts other processes by reading the `/etc/inittab` file.
`init`	10. 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.