HP-UX 10.0 System Boot and Startup White Paper HP 9000 Series 700/800 Computers April 1996, Second Edition LEGAL NOTICES The information in this document is subject to change without notice. Hewlett-Packard makes no warranty of any kind with regard to this manual, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose. Hewlett-Packard shall not be held liable for errors contained herein or direct, indirect, special, incidental or consequential damages in connection with the furnishing, performance, or use of this material. Warranty. A copy of the specific warranty terms applicable to your Hewlett-Packard product and replacement parts can be obtained from your local Sales and Service Office. Restricted Rights Legend. 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OSF/Motif is a trademark of the Open Software Foundation, Inc. in the U.S. and other countries. Second Edition: April (HP-UX Release 10.20) ============================================================================== HP-UX 10.X System Boot and Startup ================================== ----------------------------------------------------------------- NOTE: In this white paper, words in double braces ({{word}}) represents a parameter or argument that you must replace with an actual value. ----------------------------------------------------------------- >From the time you boot your system to the time you get a "login:" prompt, the system performs several important tasks automatically. The system tests computer hardware, loads and initializes HP-UX, communicates messages to users, and runs scheduled routines. When these system startup tasks are finished, HP-UX is in state where users can log in and execute processes. ----------------------------------------------------------------------------- NOTE: In case of trouble, you can boot from a recovery system (a minimal system kept on DDS media or cartridge tape). Be sure to make a recovery system as soon as you verify that the system is installed correctly. For more information, refer to the chapter "Backing Up and Restoring Data" in the HP-UX System Administration Tasks manual and the Support Media User's Manual. ----------------------------------------------------------------------------- System startup occurs in three phases: 1. The Boot ROM startup sequence (known as processor-dependent code (PDC)). 2. Intermediate level (known as a secondary loader, such as ISL). 3. The operating system startup sequence. As these phases occur, a series of messages appears quickly on the console screen. You can review HP-UX kernel messages once you have a login prompt by invoking the command /sbin/dmesg with superuser privilege. To see what happens during /sbin/rc and startup script execution, see /etc/rc.log. The Boot ROM startup sequence is different for each architecture, but the HP-UX startup sequence is similar. This white paper describes the Boot ROM startup sequence for Series 700 and 800 computers and the HP-UX startup sequence. By understanding them, you can tailor system startup to your unique needs. BOOT ROM STARTUP SEQUENCE OVERVIEW Conceptually, the boot program performs the same basic functions regardless of architecture. When the system is powered up, the boot program initializes and tests hardware to bring the system into a usable state by the operating system. This includes: * test LEDs * determine processor type * initialize and test timers * find system console and initialize video circuitry * load configuration data from EEPROM * reset and initialize I/O, including audio and HP-HIL * display copyright and Boot ROM banners, CPU type, and EEPROM status * test utility chip * test RAM, report amount of memory found and any failures * test DMA * find and report built-in interface circuits * test SCSI and LAN interfaces * display boot choices Stable storage is the non-volatile memory reserved for maintaining critical configuration parameters used during system boot. For example, the primary and alternate boot paths, console path, and autoboot settings are stored in Stable Storage. After checking the viability of the system, the boot program searches for a copy of the secondary loader. It searches a list of potential sources, including disks and network (LAN), as shown by Figure 2-1. (LIF implementation differs, depending on architecture, but the basic concept remains true.) Boot Program ----------------------------------------- | | | bootROM | | | v | _______________________ | | | | | LIF Volume | v |_____________________| ..._________________... LAN ..._________________... Figure 2-1. The Boot Program Searches for an Operating System Secondary Loader ================ The boot program software works with a specific hardware architecture. The secondary loader is a larger program, whose additional code provides the flexibility to deal with the changes to the booting process from operating-system release to release. (From the perspective of the boot program, the terms operating system and secondary loader are synonymous.) Further, the secondary loader is stored in LIF (Logical Interchange Format) disks that are understood by HP 1000, 3000, and 9000 systems. The boot program finds the secondary loader on the boot media (typically in the LIF volume of a mass storage media), loads it into memory, and starts it running. BOOT ROM STARTUP SEQUENCE (SERIES 700) The automatic boot process on the Series 700 resembles the Series 800 due to similarities in the Series 700 and 800 processor-dependent code (PDC). Switching on the system or pressing the system transfer-of-control (TOC) button causes PDC and I/O-dependent code (IODC) firmware to be executed, to verify hardware and system integrity. The PDC runs self-tests and locates the console, using IODC and the paths stored in Stable Storage. The PDC displays on the console screen copyright information, PDC and IODC ROM revisions, and amount of memory configured. (See the manual page for pdc(1M) in the HP-UX Reference.) Once checking is complete, one of two things might happen depending on your system (refer to your system's Owner's Guide for details): * If AUTOSEARCH is off, PDC searches for a potential boot device, as described in the section, "Attended Mode," which follows. * If AUTOSEARCH is on, PDC boots from Stable Storage, or searches for an appropriate path for console and boot, if any paths in Stable Storage fail. PDC displays the following to the console: Selecting a system to boot. To stop selection process, press and hold the Escape key. If the Escape key is not pressed, PDC loads the initial system loader (ISL) from the primary path in Stable Storage (for example, a SCSI disk with address scsi.6.0) and transfers control to it. The ISL, scheduled by the autoboot sequence, finds the autoexecute file and executes the command specified in it (typically "hpux" or "hpux boot disc(;0)/stand/vmunix"). By default, the autoexecute arguments load the program /stand/vmunix into memory and execute it. While loading, the secondary loader displays information about the device and file being booted, the text, data, and BSS size of the kernel and the kernel's startup address. If necessary, you have 10 seconds to override the default autoboot sequence by pressing the Escape key and enter Attended Mode. For details on the Series 700 boot capabilities, including boot sequences from a variety of devices, autoboot, and restore, see hpux(1M) in the HP-UX Reference. Also, see the Owner's Guide for your Series 700 system for information on secondary loader enhancements. Attended Mode ============= Each time the computer is powered on, you have the opportunity to interact with it by entering Attended Mode. For example, you might need to interrupt the boot sequence for either of the following reasons: * To redirect the boot sequence. * To perform a boot administration function provided by the Boot Console User Interface. Pressing the Escape key halts the automatic boot sequence and puts you into Attended Mode. The system searches the SCSI, LAN, and EISA interfaces for all potential boot devices -- devices for which boot I/O code (IODC) exists. Then, depending on your system, the system may display a table, such as the following: Device Selection Device Path Device Type and Utilities P0 scsi.6.0 QUANTUM PD210S P1 scsi.5.0 QUANTUM PD210S P2 scsi.4.0 {{DDS_tape_drive_identifier}} P3 scsi.3.0 TOSHIBA CD-ROM DRIVE:XM P4 lan.123456-789abc homebase At this point, the Boot Console User Interface main menu offers the following options: b) Boot from specified device s) Search for bootable devices a) Enter Boot Administration mode x) Exit and continue boot sequence ?) Help Using the b) option, you can direct hpux to boot from a specific device. For example, to direct hpux to boot from the QUANTUM PD210S disk drive at SCSI ID 5, you would type the key sequence "b p1". Using the s) option of the Boot Console User Interface main menu, you direct the system to search through the list of potential boot devices for only those that have a LIF volume and initial program loader (IPL). The system then displays a table listing only those devices from which you can boot. For example, a system might return the following selection: Device Selection Device Path Device Type & Utilities ---------------- ----------- ----------------------- P0 scsi.6.0 Quantum PD210S IPL P1 scsi.5.0 Quantum PD210S IPL P2 scsi.1.0 HP 2213A IPL Boot Administration Mode ------------------------ Using the a) option of the Boot Console User Interface main menu, you can enter Boot Administration mode, from which you can alter default behaviors exhibited at boot-up or obtain useful information about the hardware as configured. The following commands are available at the Boot Administration Mode menu: AUTO Display state of Autoboot/Autosearch flags AUTOSEARCH Set state of Autosearch flag AUTOBOOT Set state of Autoboot flag BOOT Boot from Primary/Alternate path or Specified Device DATE Read/Set the Real-Time Clock EXIT Return to previous menu FASTSIZE Display/Set FASTSIZE memory parameter HELP item Display Help information for item INFO Display boot/revision information LAN_ADDR Display LAN Station Address OS Display/Select Operating System PATH Display/Modify Path Information PIM_INFO Display Processor Internal Memory Information RESET Reset the System SEARCH Search for boot device SECURE Display/set secure boot mode SHOW Display the results of the previous search For detailed information on using the Boot Administration mode, see the Owner's Guide for HP-UX Users for your Series 700 system. BOOT ROM STARTUP SEQUENCE (SERIES 800) When more than one operating system is present on the system's mass storage devices, both the location of the operating systems and the type of media on which they are stored determine which operating system is loaded. The primary boot path in Stable Storage determines the default boot path. When you turn the computer on, the Boot ROM goes through the following sequence: 1. Performs System Processing Unit (SPU) self-test. 2. Reads the console path from Stable Storage, tests it, and assigns a display terminal for use as a system console. 3. Reads the boot device path from Stable Storage, or autosearches for the boot path, or lets you enter the path from the system console. 4. Loads the Initial System Loader (ISL) into memory. On Series 800 systems, storage on each disk may be divided into a set of partitions, or may be contained in a single "whole-disk" partition. For disks that are divided into partitions, the disk on which your bootable system resides has a boot area and a root partition. The boot area contains the bootstrap program and other files needed for bringing up the system. See isl(1M) in the HP-UX Reference for more information on these files. For disks that are divided into partitions, the disk partition for the boot area is typically Section 6. Root partitions are usually located on other sections of the disk. System Boot Overview ==================== The following describes what happens at powerup or reset for some systems. Refer to your system's Owner's Guide for details. At powerup or reset: 1. The processor selftest is executed from PDC (Processor Dependent Code). 2. The PDC locates the system console and tests the console path using I/O-Dependent Code. The boot and console paths are kept in Stable Storage. Stable Storage memory is static RAM. 3. The PDC checks to see if the autoboot flag is set. If not, the system asks for a boot path. If set, the system prompts the console with the following message: Booting from default path To interrupt, press any key within 10 seconds If you press a key the system asks if booting will be done from the primary autoboot path, the secondary autoboot path, or ask for an alternate path. 4. The PDC loads the ISL (Initial System Loader). The ISL loads an operating system (HP-UX in this case). Once the operating system is loaded, the Boot ROM passes program control to the operating system. The operating system then controls the system until you re-boot the system. The section in this white paper called "HP-UX Startup Sequence" describes what HP-UX does between the time it takes control and the time you see the "login:" prompt. Boot ROM Search Sequence (Series 800) ===================================== The Boot ROM initializes the primary boot path, loads ISL, and allows you to select either the manual or autoboot mode. In manual mode, you can select the boot device from all the available peripheral devices. In autoboot mode, the Boot ROM automatically boots the operating system from the primary boot path defined in Stable Storage. Autoboot -------- You should use autoboot except for first-time installation and operating system reconfiguration. The ISL "autoboot on" command enables autoboot. No reboot or automatic reboot on panic is possible. Panic is a condition when the system becomes inoperative due to an abnormal condition detected by the kernel. Before using autoboot, make sure the boot device is fully powered up and ready for operation before you turn on your computer. Autoboot is selected if you let the 10 second override period expire. Manual Boot ----------- Manual boot can be entered by pressing any key during the 10-second override period in the beginning of the autoboot sequence. When manual mode is activated, the Boot ROM prompts for the path to be used. The primary boot path is not altered or disabled. If you do not want to boot automatically from the primary boot path during the boot process, disable the autoboot flag in Stable Storage. You can do this using the ISL "autoboot off" command. However, this is not normally done because the autoboot feature makes your system administration tasks more efficient. Disabling autoboot requires your intervention each time the system is rebooted. To re-enable autoboot, use the ISL "autoboot on" command. Autosearch ---------- In the Autosearch mode, If the system cannot locate the console using the console path from Stable Storage, it searches for a console device. Then, if the system cannot locate the boot device using the primary or alternate boot paths and the autosearch flag is set, the system continues to search for a boot device. The autosearch flag is much like the autoboot flag. It is in Stable Storage and can be enabled or disabled. Use the ISL" autosearch on" command to enable autosearch and the ISL "autosearch off" command to disable the feature. When autosearch is invoked (if the two paths specified in Stable Storage fail), the following messages appear on the console: Autosearch for boot device enabled. To override, press any key within 10 seconds. If you press a key, the system responds: Do you want to continue an interactive search? (Y or N)?> If you answer "no," autosearch halts at that point and proceeds to manual boot. If you answer "yes," the system searches for a boot path, states it, and asks you if you want to boot from it. If you respond "yes," the system uses that path. Otherwise, it presents other logical paths until you respond positively or until it finds no other paths. It then proceeds to manual boot. HP-UX STARTUP SEQUENCE Once HP-UX takes control from the intermediate loader, it performs several tasks: 1. Initialize system hardware and devices. 2. Initialize HP-UX kernel data structures and interfaces. 3. Find, check, and mount the root file system. 4. Start the init process which then starts the rest of user space processes, and bring the system to the initdefault runlevel (for details, see the section "System Initialization File -- /etc/inittab" later in this paper). HP-UX initializes system hardware and devices ============================================= When the HP-UX kernel starts, it locates and initializes the system hardware, such as memory, I/O devices, bus interfaces, and devices found on I/O buses. Device drivers in the HP-UX kernel are associated to I/O devices at this time. A series of messages is printed out on the system console at this time; these messages can be reviewed later by executing the command /sbin/dmesg. HP-UX initializes kernel data structures and interfaces ======================================================= The major data structures of the HP-UX kernel are created and initialized when the kernel starts up. These data structures include the tables that describe the system processes, system memory, file systems, and devices. Status messages are also printed out to the system console at this time. Virtual memory is initialized, and the system is prepared to start user space processes. HP-UX Finds the Root File System ================================ Once HP-UX starts, it searches for the root file system. The root file system is the portion of the file system that forms the base of the global file system hierarchy -- that is, the base of the file system on which other file systems can be mounted. The root file system contains critical system files. The root file system is often found on the disk from which HP-UX booted. After finding the root file system, the operating system starts a shell to execute a series of commands from the file /sbin/pre_init_rc. Among these commands is fsck(1M), which checks the root file system, which at that point is mounted in a read-only state. (Please refer to the man page for fsck(1M) or to sections on the fsck operation in white papers on HP-UX file systems. Inconsistencies or problems noted in the file system that fsck is unable to fix at this time are corrected later by a more exhaustive fsck operation in the startup script /sbin/bcheckrc. After fsck exits, the operating system remounts the root file system in a read-write state. -------------------------------------------------------------------- CAUTION: Do not modify the /sbin/pre_init_rc script; changes made to this script may cause the system to be unbootable. -------------------------------------------------------------------- HP-UX Starts the init Process ============================= HP-UX starts the init process, /sbin/init. The init process has process ID one (1) and no parent process. The init process is ultimately responsible for starting all other user processes. The init process reads the /etc/inittab initialization file to define the environment for normal working conditions. System Initialization File -- /etc/inittab ------------------------------------------ The init process reads the /etc/inittab file one line at a time, each line containing an entry that describes an action to take. The syntax of inittab entries is: id:run-levels:action:process id One- to four-character ID that uniquely identifies the entry. run-levels Defines the run-levels in which the entry can be processed. You can specify multiple run-levels. If this field is empty, all run-levels are assumed. The following describes the run-levels: Run-Level Description --------- ----------- 1 Provides essential services, such as mounting file systems and configuring essential system parameters. 2 Used for general multi-user run state. 3 Used for export of certain types of network file systems. 4 Used for HP VUE or presentation manager startup. Typically, entries tell init to run a process at specific run-levels. If no run-levels are specified, the process can execute in any run-level. For example, the following entry tells init to run the /usr/sbin/getty process in all run-levels: cons::respawn:/usr/sbin/getty console H action Identifies what action to take for this entry. The actions are as follows: sysinit Performs system initialization on devices needed by init for obtaining run-level information at the console, such as tty characteristics. sysinit entries must finish executing before /etc/inittab continues. initdefault Causes the initial (default) run-level to be the value of the run-levels field. If more than one run-level is specified in run-levels, init uses the highest specified run-level. boot Run the command specified in the process field at boot-time only. Do not wait for process to exit before reading the next entry. Before enabling other users to access the system, init executes all /etc/inittab entries marked boot or bootwait. These processes are known as boot processes. bootwait Run the command specified in the process field at boot-time only. Wait for process to exit before reading the next entry. wait On entering the run-level that matches the run-levels field of this entry, run process and wait for it to exit before reading the next entry. respawn On entering the run-level that matches the run-levels field of this entry, run process if it is not already running. Do not wait for process to exit before reading the next entry. When the process exits, run it again. process This is a shell command to be run, if the entry's run-levels matches the run-level and/or the action field indicates such action. HP-UX recognizes any text following the # symbol as commentary. Each system architecture has its own /etc/inittab file, with some unique architecture-specific /etc/inittab characteristics. For example, systems containing graphical consoles typically start a presentation manager such as HP VUE or CDE to manage the display of multiple windows on the console. The inittab entry corresponding to the startup of such a presentation manager is as follows: vue :4:respawn:/usr/vue/bin/vuerc # VUE invocation Systems that do not contain a graphical user interface would not have such an entry in /etc/inittab. Default Run Levels -- initdefault --------------------------------- The /etc/inittab file sets up system run-levels. Run-levels are defined as collections of processes that allow the system to operate with certain properties. The entry marked initdefault sets the default run-level (typically 3 or 4): init:3:initdefault: Among the /etc/inittab entries are programs that ensure system integrity and set up essential processes. These programs are discussed in the next subheadings. Boot Check Run Command -- /sbin/bcheckrc ---------------------------------------- If you are implementing the Logical Volume Manager (LVM), bcheckrc calls /sbin/lvmrc to activate LVM volume groups. On all systems, /sbin/bcheckrc verifies that the system was properly shut down, and that file systems were consistently saved on the disk. Depending on the type of the file system, bcheckrc may invoke a series of operations such as fsck that verify file system integrity, and correct it if necessary. If a file system has become damaged and fsck cannot repair it automatically without loss of data, then bcheckrc will start a shell at the system console with the prompt "(in bcheckrc)#", instructing you to run fsck interactively. If this occurs, you must run fsck to correct the integrity of your file system. Some file system problems must be fixed in this way to minimize risk of data loss. After running fsck interactively, you may be instructed to reboot the system. If so, reboot the system using "reboot -n" to bring down the system without writing the in-core filesystem map out to disk; this maintains the disk file system's integrity. If fsck does not tell you to reboot, exit the shell by typing CTRL-D. This returns control to bcheckrc. When fsck has verified the consistency of the file systems, it exits. Initial Customization Script -- /sbin/rc ---------------------------------------- The following entry invokes /sbin/rc: sqnc::wait:/sbin/rc >/dev/console 2>&1 # system initialization The /sbin/rc script is a general purpose sequencer program that runs whenever there is a change in the system run-level (such as a change in the run-level from 2 to 3). The system executes /sbin/rc at startup as this is a change from run-level 0 (halted) to the initdefault level. /sbin/rc invokes startup scripts appropriate for the run-level. When entering state 0, /sbin/rc starts scripts in /sbin/rc0.d. When a system is booted to a particular run-level, it will execute startup scripts for all run-levels up to and including the specified level. For example, if you are booting to run-level 4, the /sbin/rc sequencer script executes the start scripts in this order: /sbin/rc1.d, /sbin/rc2.d, /sbin/rc3.d, and /sbin/rc4.d. Current start scripts and sequence numbers are listed in an accompanying file. Note that the entries on your system may vary depending on your configuration. The scripts are run in alphanumeric sequence. For a description of the script, see the ASCII-readable script file on your system. Also note that kill scripts for start scripts in directory /sbin/rc{{n}}.d reside in /sbin/rc({{n}}-1).d. The init process waits until /sbin/rc exits before processing the next entry in /etc/inittab. Terminal Processes Startup -- /usr/sbin/getty --------------------------------------------- Once /sbin/rc has finished control returns to init, which runs the commands from the process field for appropriate run-level entries in /etc/inittab. Typically, entries in /etc/inittab for a given run-level invoke the /usr/sbin/getty command, one for each terminal on which users log in. (When you add a new terminal with the SAM utility, it automatically adds an appropriate /usr/sbin/getty entry to /etc/inittab.) The /usr/sbin/getty command runs the login process on the specified terminal, allowing users to login on the terminal. For example, the following /etc/inittab entry runs a getty at the system console: cons:123456:respawn:/usr/sbin/getty console console # system console The respawn action field tells init to restart the getty process after it exits. This means that each time you log off the system console, a new "login:" prompt is displayed, so you can log in the next time. The 123456 run-levels field indicates that init runs getty in run-levels 1 through 6. The default configuration for /etc/inittab invokes /usr/sbin/getty only for the system console. If your system has additional terminals on which you wish to support logins, you must add the appropriate getty entries to /etc/inittab. (Note, however, that SAM automatically creates these entries when you use it to add terminals). The /usr/sbin/getty command is the first command executed for each login terminal. It specifies the location of the terminal and its default communication protocol, as defined in the /etc/gettydefs file. It prints the /etc/issue file (if present) and it causes the first "login:" prompt to be displayed. Eventually, the getty process is replaced by your shell's process (see the "Login" white paper). When you logout, the /sbin/init process is signaled and takes control again. The init process then checks /etc/inittab to see if the process that signaled it is flagged as continuous (denoted by respawn). If the process is continually respawned, init again invokes the command in the command field of the appropriate inittab entry as described above (that is, the getty runs and a new "login:" prompt appears). If the process is not flagged as continuous, it is not restarted. --------------------------------------------------------------------- NOTE: Do not add /usr/sbin/getty entries to /etc/inittab for unconfigured terminals, unless action is "off". --------------------------------------------------------------------- If the system finds itself having to respawn entries too rapidly, it assumes that a problem exists and goes to sleep for five minutes before trying to respawn again. If the problem involves the getty for the system console, the system might not be bootable without repair. Users can log in at all terminals for which getty processes have been executed. Powerfail Routines -- /sbin/powerfail ------------------------------------- A local powerfail is a power failure that halts the computer by affecting its central bus. On some architectures, the HP-UX operating system provides a mechanism for recovery from a local powerfail to ensure that any program running on the system at the time of failure can resume executing when power to the bus is restored. The HP-UX kernel must be correctly configured to support the powerfail operation. You can change the value of the powerfail variable (the default is zero) by using the reconfiguring the kernel section of sam(1M). Then, if need be, powerfail can be disabled by reconfiguring an operating-system parameter as follows: pfail_enabled 0; After the hardware detects a powerfail condition and notifies the HP-UX kernel, the kernel invokes user space processes to handle the event. The powerfail routine that will be invoked when powerfail is detected is configured as an entry in the file /etc/inittab: powf::powerwait:/sbin/powerfail >/dev/console 2>&1 #power fail routines The /sbin/powerfail script is an executable script that can be customized by users. The script is separated into three parts: 1. A script of configuration variables. 2. An HP-supplied execution script in the /sbin or /usr/sbin directory. 3. A user-modifiable script that users can customize as they need. The configuration variables for powerfail reside in the /etc directory and follow the same rules as /etc/rc.config files. The powerfail execution script resides under the /sbin or /usr/sbin directories and cannot be modified. At the end of an HP-supplied script, users can add their own commands. These scripts reside in /etc/local/%%script_name%%. For example, /sbin/powerfail can look like this: source /etc/powerfail.cfg {{HP commands}} {{Additional HP commands}} source /etc/local/powerfail where the contents of /etc/powerfail.cfg is: VARIABLE=VALUE VARIABLE2=VALUE2 and the contents of /etc/local/powerfail are user-chosen commands. Be sure to follow guidelines for correct shutdown and start-up of a system necessitated by powerfail. These guidelines are given in Chapter 3, "Starting and Stopping HP-UX" of the HP-UX System Administration Tasks manual. For More Information -------------------- The sections in this white paper describe the default operation of the system as shipped to you. However, by altering certain configuration or system files, any of the procedures can change. If, for example, you write your own /sbin/rc script, the paragraphs which follow may no longer apply. Table 2-2 shows where to look for additional information. Table 2-2. Additional Startup Information --------------------------------------------------------------------- To Learn More About... || Refer to... --------------------------------------------------------------------- /sbin/init || init(1M) in the HP-UX Reference /etc/inittab || inittab(4) in the HP-UX Reference /sbin/bcheckrc || /sbin/bcheckrc file /sbin/rc || /sbin/rc file /usr/sbin/getty || getty(1M) in the HP-UX Reference [Search Screen][Search Results][Search History][Document Display] [HP Electronic Support Center] (c) Copyright 1996 Hewlett-Packard Company.