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REBOOT(8)                   System Manager's Manual                  REBOOT(8)



NAME
       reboot - UNIX bootstrapping procedures

SYNOPSIS
       /etc/reboot [ -n ] [ -q ]

DESCRIPTION
       UNIX  is started by placing it in memory at location zero and transfer-
       ring to zero.  Since the system is not reenterable, it is necessary  to
       read it in from disk or tape each time it is to be bootstrapped.

       Rebooting  a  running  system.   When a UNIX is running and a reboot is
       desired, shutdown(8) is normally used.  If  there  are  no  users  then
       /etc/reboot  can  be  used.   Reboot causes the disks to be synced, and
       then a multi-user reboot  (as  described  below)  is  initiated.   This
       causes  a  system  to  be booted and an automatic disk check to be per-
       formed.  If all this succeeds without  incident,  the  system  is  then
       brought up for many users.

       Options to reboot are:

       -n     option avoids the sync.  It can be used if a disk or the proces-
              sor is on fire.

       -q     reboots quickly and ungracefully, without shutting down  running
              processes first.

       Power fail and crash recovery.  Normally, the system will reboot itself
       at power-up or after crashes.  Provided the auto-restart is enabled  on
       the  machine  front  panel,  an automatic consistency check of the file
       systems will be performed then and unless this fails  the  system  will
       resume multi-user operations.

       Cold  starts.  These are processor type dependent.  On an 11/780, there
       are two floppy files for each disk  controller,  both  of  which  cause
       boots  from  unit  0 of the root file system of a controller located on
       mba0 or uba0.  One gives a single user shell, while the  other  invokes
       the  multi-user automatic reboot.  Thus these files are HPS and HPM for
       the single and multi-user boot from MASSBUS RP06/RM03/RM05  disks,  UPS
       and  UPM  for  UNIBUS  storage  module controller and disks such as the
       EMULEX SC-21 and AMPEX 9300 pair, or HKS and HKM for RK07 disks.

       Giving the command

              >>>BOOT HPM

       Would boot the system from (e.g.) an RP06 and run the automatic consis-
       tency check as described in fsck(8).  (Note that it may be necessary to
       type control-P to gain the attention of the LSI-11 before  getting  the
       >>> prompt.)  The command

              >>>BOOT ANY

       invokes  a  version  of  the  boot program in a way which allows you to
       specify any system as the system to be booted.  It reads from the  con-
       sole a device specification (see below) followed immediately by a path-
       name.

       On an 11/750, the reset button will boot from the  device  selected  by
       the front panel boot device switch.  In systems with RK07's, position B
       normally selects the RK07 for boot.  This  will  boot  multi-user.   To
       boot from RK07 with boot flags you may specify

              >>>B/n DMA0

       where,  giving  a n of 1 causes the boot program to ask for the name of
       the system to be bootstrapped, giving a n of 2 causes the boot  program
       to  come  up  single user, and a n of 3 causes both of these actions to
       occur.

       The 11/750 boot procedure uses the boot roms to load block 0 off of the
       specified  device.   The /usr/mdec directory contains a number of boot-
       strap programs for the various disks which should be placed  in  a  new
       pack  automatically by newfs(8) when the ``a'' partition file system on
       the pack is created.

       On both processors, the boot program finds the  corresponding  file  on
       the given device, loads that file into memory location zero, and starts
       the program at the entry address specified in the program header (after
       clearing off the high bit of the specified entry address.)  Normal line
       editing characters can be used in specifying the pathname.

       If you have a MASSBUS disk and wish to boot off of a file system  which
       starts  at  cylinder  0  of unit 0, you can type "hp(0,0)vmunix" to the
       boot  prompt;   "up(0,0)vmunix"   would   specify   a   UNIBUS   drive,
       ``hk(0,0)vmunix''  would  specify an RK07 disk drive, ``ra(0,0)vmunix''
       would specify a UDA50 disk drive, and ``rb(0,0)vmunix'' would specify a
       disk on a 730 IDC.

       A device specification has the following form:

              device(unit, minor)

       where  device  is the type of the device to be searched, unit is 8* the
       mba or uba number plus the unit number of the device, and minor is  the
       minor  device  index.  The following list of supported devices may vary
       from installation to installation:
            hp   MASSBUS disk drive
            up   UNIBUS storage module drive
            ht   TE16,TU45,TU77 on MASSBUS
            mt   TU78 on MASSBUS
            hk   RK07 on UNIBUS
            ra   storage module on a UDA50
            rb   storage module on a 730 IDC
            rl   RL02 on UNIBUS
            tm   TM11 emulation tape drives on UNIBUS
            ts   TS11 on UNIBUS
            ut   UNIBUS TU45 emulator

       For tapes, the minor device number gives a file offset.

       In  an  emergency,  the  bootstrap  methods  described  in  the   paper
       ``Installing  and Operating 4.2bsd'' can be used to boot from a distri-
       bution tape.

FILES
       /vmunix           system code
       /boot             system bootstrap

SEE ALSO
       crash(8V), fsck(8), init(8), rc(8), shutdown(8), halt(8), newfs(8)



4th Berkeley Distribution         10 May 1981                        REBOOT(8)