boot(8)                 OpenBSD System Manager's Manual                boot(8)

NAME
     boot - system bootstrapping procedures



DESCRIPTION
     Power fail and crash recovery

     When the OpenBSD kernel is booted normally (using one of the two methods
     discussed below), it initializes itself and proceeds to boot the system.
     An automatic consistency check of the file systems takes place, and un-
     less this fails, the system comes up to multi-user operations.  The prop-
     er way to shut the system down is with the shutdown(8) command.

     If the system crashes, it will enter the kernel debugger, ddb(8) ,if it
     is configured in the kernel.  If the debugger is not present, or the de-
     bugger is exited, the system will attempt a dump to the configured dump
     device (which will be automatically recovered with savecore(8) during the
     next boot cycle).  After the dump is complete (successful or not), the
     system will attempt a reboot.

     Booting OpenBSD using the bootloader

     When a bootable OpenBSD partition is created by means of installboot(8) ,
     the Atari BIOS will automatically start the OpenBSD bootloader. By de-
     fault it will load the kernel image /bsd and attempts to boot it into
     multi-user mode. This behaviour can be changed by either keeping the
     Alternate or the Right-Shift key pressed during the boot. When the
     Alternate key is pressed, the bootstrap is aborted, causing the BIOS to
     continue scanning the disks for a bootable partition (this is compatible
     with AHDI 3.0). Pressing the Right-Shift key during the boot, causes the
     boot loader to enter the interactive mode.  In interactive mode, the com-
     mand line looks like:


           [OS-type] [boot-path] [boot-options]

     Each component of the command can be ommitted in which case the defaults
     indicated will be used.

     OS-type:
       .OpenBSD (the default)
       .linux
       .asv
       .tos

       If something other than .OpenBSD is specified, control is returned to
       the BIOS with the boot preference set to the selected type. Due to lim-
       itations of the BIOS however, the search for bootblocks is continued
       rather than restarted.

     boot-path
       This gives you the opportunity to boot another kernel, say: /bsd.old.
       The default is /bsd

     boot-options
       These options are a subset of the loadbsd options.
       -a    Boot into multi-user mode (the default)
       -b    Ask for a root device
       -d    Enter the kernel debugger

     Booting using the loadbsd program

     When you want (or have to) start OpenBSD from GEM, you have to use the
     loadbsd program that is supplied on the kernel-floppy. The loadbsd com-
     mand line specification is:

           loadbsd [-abdhstwDV] [-S amount] [-T amount] kernel-path

     Description of options:

     -a    Boot automatically into multi-user mode.

     -b    Ask for the root device the kernel must use.

     -d    Enter the kernel debugger after booting.

     -h    Print a help screen that tries to explain the same options as men-
           tioned here.

     -o outputfile
           Write all output to the file outputfile.

     -s    Tell OpenBSD only to use ST compatible RAM.

     -t    Test loading of the kernel but don't start OpenBSD.

     -w    Wait for a keypress before exiting loadbsd. This is useful when
           starting this program under GEM.

     -D    Show debugging output while booting the kernel.

     -S amount
           Set the amount of available ST compatible RAM in bytes. Normally
           this value is set automatically from the values initialized by the
           BIOS.

     -T amount
           Set the amount of available TT compatible RAM in bytes. Normally
           this value is set automatically from the values initialized by the
           BIOS.

     -V    Print the version of loadbsd that you are using.

     kernel-path
           This is a GEMDOS path specification of the kernel to boot.

     Note: Because the loadbsd program can only read kernels from a GEMDOS
     filesystem, the file /bsd is usually not the same as the actual kernel
     booted. This can cause some programs to fail.

FILES
     /bsd  system kernel

SEE ALSO
     ddb(8),  savecore(8),  shutdown(8)


OpenBSD 2.3                      June 21, 1996                               2