boot man page on OpenBSD

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BOOT(8)		   OpenBSD System Manager's Manual (Zaurus)	       BOOT(8)

     boot, boot.conf - zaurus-specific second-stage bootstrap

     The main purpose of this program is to load the system kernel while
     dealing with the peculiarities of the zaurus machine.

     As described in boot_zaurus(8), this program is loaded by the primary
     bootstrap loader and provides a convenient way to load the kernel.	 This
     program acts as an enhanced boot monitor for zaurus systems, providing a
     common interface for the kernel to start from.

     Basic operations include:

     o	 Detecting and switching between multiple consoles.
     o	 Loading kernels from any device supported by the primary bootstrap
     o	 Passing system parameters queried from the primary bootstrap loader
	 to the kernel.
     o	 Providing an interactive command line.

     The sequence of its operation is as follows: initialization, parsing the
     configuration file, then an interactive command line.  While at the
     command line you have 5 seconds to type any commands, if needed.  If time
     expires, the kernel will be loaded according to the current variable
     settings (see the set command).  Each time a kernel load fails, the
     timeout is increased by one second.  The sequence of boot operations is
     as follows:

     1.	  Probe for console devices, which includes the (default) LCD+Keyboard
	  console (cn0) and up to three serial consoles (com0 through com2)
	  connected to the serial ports.  Display messages to the default
	  console about the devices found.

     2.	  Probe for disk devices, and select the first disk with an i386-
	  compatible MBR and a valid OpenBSD primary partition.

     3.	  If the file /etc/boot.conf exists on the root filesystem on the
	  selected disk, open and parse it.  This file may contain any
	  commands boot accepts at the interactive prompt.  Though default
	  settings usually suffice, they can be changed here.

     4.	  The header line

		>> OpenBSD/zaurus BOOT [x.xx]

	  is displayed to the active console, where x.xx is the version number
	  of the boot program, followed by the


	  prompt, which means you are in interactive mode and may enter
	  commands.  If you do not, boot will proceed to load the kernel with
	  the current parameters after the timeout period has expired.

     By default, boot attempts to load the kernel executable /bsd.  If it
     fails to find the kernel and no alternative kernel image has been
     specified, the system will be unable to boot.

     The following commands are accepted at the boot prompt:

     boot [image [-acds]]
	      Boots the kernel image specified by image with any options
	      given.  Image specification consists of a pair device:filename;
	      either or both can be omitted (`:' is not needed if both are
	      omitted), in which case values from boot variables will be used.

	      When selecting the device to boot from, boot makes no
	      distinction between SCSI and IDE type drives; they are detected
	      as `hd' devices.	Therefore, to boot kernel /bsd from slice `a'
	      on the first hard drive (irrespective of device type), specify
	      ``boot hd0a:/bsd''.

	      Note: Normally, the internal hard disk is designated by the
	      device name `hd0'.  If a CF hard disk is present in the socket
	      when the system starts, the internal hard disk is instead
	      designated by the prefix `hd1', and `hd0' will access the CF
	      hard disk.

	      -a   Causes the kernel to ask for the root device to use.

	      -c   Causes the kernel to go into boot_config(8) before
		   performing autoconf(4) procedures.

	      -d   Causes the kernel to drop into ddb(4) at the earliest
		   convenient point.

	      -s   Causes the kernel to boot single-user.

     clear    Clears the console screen.  This is useful if your bootstrap
	      console doesn't scroll the screen automatically when the cursor
	      is in the bottom line.

     echo [args]
	      Displays args on the console device.

     help     Prints a list of available commands and machine dependent
	      commands, if any.

     ls [directory]
	      Prints contents of the specified directory in long format
	      including: attributes and file type, owner, group, size,

     reboot   Returns control to the primary bootstrap loader.

     set [varname [value]]
	      If invoked without arguments, prints a list of variables and
	      their values.  If only varname is specified, displays contents
	      of that variable.	 If varname and value are both specified, sets
	      that variable to the given value.	 Variables include:

	      addr     Address at which to load the kernel.
	      debug    Debug flag if boot was compiled with DEBUG defined.
	      device   Boot device name (e.g., hd0a).
	      howto    Options to pass to the loaded kernel.
	      image    File name containing the kernel image.
	      timeout  Number of seconds boot will wait for human intervention
		       before booting the default kernel image.
	      tty      Active console device name (e.g., cn0, com0, com1).

     stty [device [speed]]
	      Displays or sets the speed for a console device.	If changing
	      the baudrate for the currently active console, boot offers you
	      five seconds of grace time before committing the change to allow
	      you to change your terminal's speed to match.  If changing speed
	      not for the active console, the baudrate is set for the next
	      time you switch to a serial console.

	      The default baudrate is 9600bps.

     time     Displays system time and date.

     Since the bootblocks actually live in a Linux flash filesystem, a rather
     obtuse method must currently be used to upgrade them.

	   1.	Place zboot and zbsdmod.o onto an MS-DOS filesystem on a CF
		card, and then insert into the Zaurus.
	   2.	Remove power from the Zaurus.
	   3.	Unplug the battery.
	   4.	Start holding down the `b' and `d' keys.
	   5.	Wait 30 seconds, then re-insert the battery and power up the
	   6.	When you see text start to appear on the Zaurus, release the
		`b' and `d' keys.
	   7.	Login as root and perform the following steps:

		      # mount /dev/mtdblock2 /tmp
		      # cp /mnt/cf/z* /tmp/home/etc/rc.d
		      # reboot

		An SD card with an MS-DOS filesystem may be used instead, in
		which case the Linux pathname will be /mnt/card instead of

     /usr/mdec/zbsdmod.o  kernel module for the primary bootstrap loader that
			  must be loaded before the system bootstrap
     /usr/mdec/zboot	  system bootstrap
     /etc/boot.conf	  system bootstrap's startup file
     /bsd		  kernel image
     /bsd.rd		  kernel image for installation/recovery

     Boot the default kernel:

	   boot> boot

     Remove the 5 second pause at boot-time permanently, causing boot to load
     the kernel immediately without prompting:

	   # echo "boot" > /etc/boot.conf

     Use serial console.  A null modem cable should connect the specified
     serial port to a terminal.	 Useful for debugging.

	   boot> set tty com0

     Invoke the serial console at every boot:

	   # echo "set tty com0" > /etc/boot.conf

     Boot the kernel named /bsd from the second hard disk in ``User Kernel
     Configuration'' mode (see boot_config(8)).	 This mechanism allows for the
     explicit enabling and disabling of devices during the current boot
     sequence, as well as the modification of device parameters.  Once booted,
     such changes can be made permanent by using config(8)'s -e option.

	   boot> boot hd1a:/bsd -c

     autoconf(4), ddb(4), boot_config(8), boot_zaurus(8), fdisk(8), reboot(8)

     This program was written by Michael Shalayeff for OpenBSD 2.1, and
     adapted to zaurus by Uwe Stuehler for OpenBSD 3.7.

     Non-IDE disks can not be used to load /etc/boot.conf or the kernel from

OpenBSD 4.9			 May 31, 2007			   OpenBSD 4.9

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