boot(8) - NetBSD Manual Pages

BOOT(8)               NetBSD/pmax System Manager's Manual              BOOT(8)


NAME

     boot -- system bootstrapping procedures


DESCRIPTION

     The NetBSD kernel is started by placing it near the beginning of physical
     memory and transferring to the entry point.  Since the system is not
     reenterable, it is necessary to read it in from disk or tape each time it
     is to be bootstrapped.

   Power fail and crash recovery
     Normally, the system will boot itself at power-up or after crashes.  An
     automatic consistency check of the file systems will be performed, and
     unless this fails, the system will resume multi-user operations.

   Cold starts
     At power up, all DECstation ROMs consult the haltaction environment vari-
     able in EEPROM to determine whether or not to attempt to boot automati-
     cally.  If this variable is set to `h', the ROM prints a prompt on the
     console and waits for user commands.  If set to `b', the ROM attempts to
     autoboot.

DECSTATION 2100 and 3100
     On the DECstation 2100 and 3100, the path used for automatic booting is
     stored in the bootpath environment variable.
      The path is made up of a device type specifier (e.g., rz, tz, mop or
     tftp) followed by a triplet in the form (x,y,z), followed by a filename
     to load.

     Within the triplet, x is the controller (always 0), y is the SCSI id of
     the drive to boot from or 0 for net boots, and z is the partition to boot
     from (usually 0 for SCSI devices, always zero for network booting).  For
     both disk and network boots, () may be specified instead of (0,0,0).

     The filename is optional for bootp/tftp and mop booting, since in these
     cases the network protocol can be used to determine which file to boot.
     When booting off the tape, no filename should be specified.  When booting
     off of disk, the filename is optional but is usually specified.  If no
     filename is specified when booting off disk, the following filenames are
     tried in order: netbsd.pmax, netbsd, netbsd.gz, netbsd.bak, netbsd.old,
     onetbsd, gennetbsd.  Generally, the kernel is named netbsd.

     An example bootpath setting would be:
           setenv bootpath rz(0,1,0)netbsd

     At the PROM prompt, the user may boot NetBSD with either the auto or the
     boot command.  If the auto command is used, the -a argument is passed to
     the kernel, requesting a multi-user boot; otherwise the -s argument is
     passed, requesting that NetBSD boot to single user mode.

     When either the boot or the auto command is issued with no arguments, the
     kernel specified in the bootpath environment variable is booted.  With
     the boot command, an alternative kernel may be specified with the -f
     flag, followed by the path of the kernel to boot, as described above.
     For example:
           boot -f rz(0,4,0)netbsd.new

TURBOchannel DECstations
     On TURBOchannel machines (all DECstation 5000 models), the boot path is
     specified in the boot environment variable, along with any arguments to
     be passed to the kernel.  Note that to specify boot arguments (e.g., -a)
     when setting the boot environment variable, the filename and arguments
     must be enclosed in quotes.  For example:
           setenv boot ``3/rz4/netbsd -a''

     The device from which to boot is specified as the TURBOchannel slot num-
     ber, a TURBOchannel-option-specific device name, and a path to the file
     to load, all separated by slashes.  You can get a list of the devices
     installed in your TURBOchannel slots (as well as any built-in devices
     which appear as TURBOchannel slots) by typing the cnfg command at the
     boot prompt.  You can get more detailed information about a specific TUR-
     BOchannel option by typing cnfg followed by the slot number of that
     option.

     For SCSI devices, the option-specific device identifier is either rz# for
     disks or tz# for tapes, where # is the SCSI id of the device.  For net-
     work devices, the option-specific protocol identifier is either mop or
     tftp.  Filename requirements are as for the DECstation 2100 and 3100.

     To start NetBSD from the boot prompt, the boot command must be used.
     With no arguments, this simply boots the default kernel with the default
     arguments as set with setenv boot.  If no boot environment variable is
     set or if an alternative kernel is to be booted, the path of that kernel
     may be specified after the boot command as described above, and any argu-
     ments may be passed similarly.  For example:
           boot 3/rz4/netbsd.new -a


KERNEL ARGUMENTS

     The kernel supports the following arguments:

           a    Autoboot -- try and boot to multi-user mode without further
                input.

           m    Use a miniroot already present in memory.

           n    Prompt for the root file system device, the system crash dump
                device, and the path to init(8).

           N    Do not prompt for the root file system device, the system
                crash dump device, and the path to init(8).  If the config-
                ured-in devices are present, use them.

           s    Boot only to single-user mode.

     Since DECstation PROMs also parse any arguments with a leading "-", and
     reject unrecognized options, arguments other than "a" or "s" should be
     specified after the kernel name with no leading "-".  For example:
           boot 3/rz4/netbsd ns


SEE ALSO

     ddb(4), halt(8), init(8), installboot(8), rc(8), reboot(8), savecore(8),
     shutdown(8)


HISTORY

     The boot command is currently under development.

NetBSD 10.99                     April 8, 2003                    NetBSD 10.99