BOOT(8) BOOT(8)
NAME
boot - connect to the root file server
SYNOPSIS
/boot [ -afkmp ] [ -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.
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 is dependent 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 and the Safari, no information is passed
from the boot ROM or program. Their command lines are
/68020/9nextstation -p
and
/386/9safari -p
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. If the -m or
-p option is given (or the method on the command line is
invalid) boot will prompt for these.
Method and address are prompted for first. The prompt lists
all valid methods, the default in brackets.
root is from (il, tcp, hs, local)[il]:
A newline picks the default. Other possible responses are
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method or method!address.
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:
If the method chosen is anything other than local 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 mount's 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 /$objtype/init -t. If the -a or -m options are
given they are also passed as options to init.
CPU Servers
The user owning devices and console processes on CPU servers
is always bootes. It is immutable. (The name is compiled
into the system as the value of the variable eve; local
sites may choose a different name.) If a -k option is given
boot will prompt for an encryption key to be stored in the
CPU server's non-volatile ram.
key:
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This key is used to verify to callers of the CPU server that
it is indeed the server being called.
Once connected, boot mount's the root file system before /
and makes the connection available as #s/boot for subsequent
processes to mount (see bind(2)). Boot completes by
exec(2)'ing /$objtype/init -c. If the -a or -m options are
given they are also passed as options to init.
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 DARPA Internet methods, il and tcp, the address must
be a numeric IP address. If no address is specified a file
server address will be found from another system on the net-
work 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
SEE ALSO
root(3), bootp(8), init(8)
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