The Boot Process

1
The Boot Process

• ICE System Consultant Group 2nd
• 2002? 5? 24?

2
System Boot PROM Phase

• It runs self-test diagnostics.
• Hardware, memory
• It displays the system identification banner.
• Model, keyboard, PROM vision, RAM, serial
  num.,Ethernet add., host ID
• It reads the disk label located at sector 0 on
  the default boot device.
• It finds the boot program form the default boot
  device programming into PROM
• Boorblk(sector 1-15)
• It loads the boot program
• /platform/uname m/ufsboot

3
System Boot Cycle
Kernel Initialization phase
Boot program phase

• .

PROM runs
Load kermel modules
Ufsboot
OK printenv boot-devices
32 or 64 bit kernel
Read /etc/system file
Ok boot Read disk label(sector0)
Kernel initializes itself And start the init
process
Boot PROM phase
Reads boot block (sector0-15)
The init process starts the runcontrol script
PROM loads boot block (bootblk) program
The /sbin/init phase
4
Autoconfiguration Process

• Kernel modules loaded on demand
• Kernel modules loaded into memory
• Kernel configured dynamically

5
Auto configuration Process

• 64-bit kernel
• /platform/uname m/kernel/sparcv9/unix
• /platform/uname m/kernel/sparcv9/genunix
• 32-bit kernel
• /platform/uname m/kernel/unix
• Subdirectory
• drv device drivers pseudo device drivers
• exec
• fs file system modules
• misc miscellaneous modules
• sched
• strmod
• sys

6
The /etc/system File

• Customize to change kernel configuration process
• Moddir variable
• Rootdev variable root device????
• Exclude variable - autoconfiguration
• Forceload variable memory ??
• Set variable
• Override default value using variablevalue

7
Kernel Rebuild

• PROM mode
• Ok boot r
• OS mode(shutdown)
• reboot -- -r
• OS mode(non-shutdown)
• drvconfig

8
The /sbin/init Phase

• Main roles
• It creates processes which bring the system up to
  the default run level
• It controls transition between run states by
  rereading the /etc/inittab file

9
Boot Terminology

• Run levels
• 0(PROM),
• 1(single user, file system mount)
• 2(multiuser, without NFS)
• 3(multiuser, with NFS)
• 4(not used)
• 5(halt)
• 6(reboot)
• S or s(singe user mode)
• Run control scripts
• Single-user mode(1 and S level)
• Multi-user mode(2 and 3 level)

10
The /etc/inittab File

• /etc/inittab
• fssysinit/sbin/rcS gt/dev/console 2gt1
  lt/dev/console
• is3initdefault
• p3s1234powerfail/usr/sbin/shutdown -y -i5 -g0
  gt/dev/console 2gt1
• s223wait/sbin/rc2 gt/dev/consol
• sc234respawn/usr/lib/saf/sac -t 300

11
The init Process and the /etc/inittab File
Set initdefault to level3 Run entries with
sysinit in action filed Run entries with 3 in
restate filed
Init process
12
The /etc/rc.d Directories

• Uppercase K0-90-9A-z0-9 -gt kill
• Uppercase S0-90-9A-z0-9 -gt Start
• File name starting with lowercase letters will
  not be run
• The /etc/init.d Directory
• Hard link -gt /etc/rc.d
• ln -s symbolic link

13
Run Control Files

• Identify the run level for the service.
• Determine which services are needed by the new
  process.
• Create the startup (shutdown) scrip in
  /etc/init.d for each service.
• Change to the appropriate /etc/rc.d and create
  hard links to the new /etc/init.d scripts.
• Repeat the process for the directory containing
  the shutdown script.
• Test

14
Run Control Cycle

• /sbin/rc0
• system services and all running process are
  stopped
• /sbin/rc1
• userlogin disable, remote file system unmounted.
• /sbin/rc2
• /sbin/rc3
• /sbin/rc5
• /sbin/rc6
• /sbin/rcS