BOOT(8)                                                   BOOT(8)

     NAME
          boot - connect to the root file server

     SYNOPSIS
          /boot [ -fkm ] [ -uusername ] [ method!fs-addr ]

     DESCRIPTION
          Boot is the first program run after a kernel has been
          loaded.  It connects to the file server that will serve the
          root, performs any authentication needed to connect to that
          server, and exec(2)'s the init(8) program.  It is started by
          the kernel, never run directly by the user.  See booting(8)
          for information about the process of loading the kernel (and
          boot) into memory.

          Once loaded, the kernel initializes its data structures and
          devices.  It sets the two environment variables /env/cputype
          and /env/terminal to describe the processor.  It then binds
          a place-holder file server, root(3), onto / and crafts an
          initial process whose sole function is to exec(2) /boot, a
          binary which is compiled into root(3).

          The command line passed depends on the information passed
          from boot ROM to kernel.  On the MIPS Magnum and SGI Power
          Series the command line passed to boot is the same as that
          given to the ROM monitor.

          On AT&T Gnots the command line is

               /68020/9gnot method!server

          On the Nextstation , no information is passed from the boot
          ROM or program.  The command line is

               /68020/9nextstation

          On the PC, each line in the DOS file plan9.ini of the form
          name=value is passed to the boot program as an environment
          variable with the same name and value.  The command line is

               /386/9pc method!server

          Boot must determine the file server to use and a method with
          which to connect to it.  It must also set a user name to be
          used as the owner of devices and all console processes and
          an encryption key to be used when challenged.  Boot will
          prompt for these.

          Method and address are prompted for first.  The prompt lists
          all valid methods, with the default in brackets.

     BOOT(8)                                                   BOOT(8)

               root is from (il, tcp, hs, local)[il]:

          A newline picks the default.  Other possible responses are
          method or method!address.  To aid in automatic reboot, the
          default is automatically taken on CPU servers if nothing is
          typed within 15 seconds.

          The other interactions depend on whether the system is a
          terminal or a CPU server.

        Terminal
          The terminal must have a username to set.  If none is speci-
          fied with the -u option, boot will prompt for one on the
          console:

               user:

          The user will also be prompted for a password to be used as
          an encryption key on each attach(5):

               password:

          With most methods boot can now connect to the file server.
          However, with the serial line methods 9600 and 19200, the
          actual mechanics of setting up the complete connection are
          too varied to put into the boot program.  Instead boot lets
          the user set up the connection.  It prints a prompt on the
          console and then simulates a dumb terminal between the user
          and the serial line:

               Connect to file system now, type ctrl-d when done.
               (Use the view or down arrow key to send a break)

          The user can now type at a modem or a Datakit destination
          please: interface to set up the connection to a TSM8 card.
          At Murray Hill, a user would type nj/astro/plan85 at this
          point.  When the user types a control-D, boot stops simulat-
          ing a terminal and starts the file system protocol over the
          serial line.

          Once connected, boot mounts the root file system before /
          and makes the connection available as #s/boot for subsequent
          processes to mount (see bind(2)). Boot completes by
          exec(2)'ing /$objtype/init -t.  If the -m option is given it
          is also passed as an option to init.

          If the kernel has been built with the cache file system,
          cfs(4), the local disk partition /dev/[sh]d[01]cache exists,
          and the root file system is from a remote server, then the
          kernel will insert a user level cache process between the
          remote server and the local namespace that caches all remote
          accesses on the local partition.  The -f flag commands cfs

     BOOT(8)                                                   BOOT(8)

          to reformat the cache partition.

        CPU Servers
          The user owning devices and console processes on CPU servers
          and that user's domain and encryption key are read from
          NVRAM on all machines except PC's.  PC's keep the informa-
          tion in the disk partition /dev/[sh]d[01]nvram.  If a -k
          option is given or if no stored information is found boot
          will prompt for all three items and store them.

               password:
               authid: bootes
               authdom: research.att.com

          The key is used for mutual authentication of the server and
          its clients.  The domain and id identify the owner of the
          key.

          Once connected, boot behaves as on the terminal except for
          exec(2)'ing /$objtype/init -c.

        Booting Methods
          The methods available to any system depend on what was com-
          piled into the kernel.  The complete list of booting methods
          are listed below.

          cyc     connect via a point-to-point fiber link using
                  Cyclone boards.  If specified, the address must be
                  the number of the Cyclone board to be used, default
                  0.

          il      connect via Ethernet using the IL protocol.

          tcp     connect via Ethernet using the TCP protocol.  This
                  method is used only if the initial file server is on
                  a Unix system.

          hs      connect via Datakit using the high speed Datakit
                  card.

          incon   connect via Datakit using the Incon interface.

          9600    connect via Datakit using the serial interface at
                  9600 baud.

          19200   connect via Datakit using the serial interface at
                  19200 baud.

          local   connect to the local file system.

          For the il and tcp methods, the address must be a numeric IP
          address.  If no address is specified, a file server address

     BOOT(8)                                                   BOOT(8)

          will be found from another system on the network using the
          BOOTP protocol and the Plan 9 vendor-specific fields.  For
          the Datakit methods, hs, 9600, 19200, and incon, the address
          must be specified and must be a relative path name to the
          file server.  If no address is specified, the address Nfs is
          used.

     FILES
          #s/boot

     SOURCE
          /sys/src/9/boot

     SEE ALSO
          root(3), bootp(8), init(8)