plan9rc is the script run after boot(8).  It supports several new
options in plan9.ini.  "interactive=yes" changes the boot process to
an interactive question-and-response format where all variables can be
changed from their defaults and the possibility of dropping to a shell
is available.  "interactive=no" turns off all prompts.  The default
behavior is equivalent to "interactive=traditional".  "ramsetup="
provides the name of a command to set up an initial skeleton
filesystem on a ramdisk.  The default is the provided ramskel script
compiled into the kernel /boot/bootpaq, which expands /boot/skel.tar.
If "tgzfs=tools.tgz" then an additional root filesystem of this name
will be expanded from the 9fat partition.  The "fatpath=" variable is
used to specify the location of the 9fat, if not /dev/sdC0/9fat.
"factotum=" specifies either cpu, terminal, or user parameters to
start factotum.  "rootstart=" specifies either cpu, terminal, other or
none parameters as the final system startup script.  These default to
the setting in /env/service.

There are tools provided to use the interactive startup as
autoconfiguration.  run savecfg to store a copy of the curent config
in /tmp/p9cfg which can be pasted into plan9.ini as a menuitem.

full list of variables: bootparse is a copy of bootargs as described
by boot(8) and plan9.ini(8), not set as separate var factotum - type
of factotum [cpu terminal debug] sysname - standard sysname from
plan9.ini ramsetup - program to set up ramfs for bootscripts, defaults
to ramskel startventi - set to yes to start the venti server [yes]
getrootfs - determined from bootparse or set by user during
interactive [tcp local] fs - standard fs address from plan9.ini,
needed for tcp booting auth - standard auth address for tcp booting
venti - standard venti address variable from plan9.ini fossil -
standard fossil address from plan9.ini not parsed fully correctly in
general cfs - standard cfs address from plan9.ini initscript - script
forked off into namespace provided initskel begins cpu server on 17020
namespace - namespace for starting initscript rootstart - whether or
not to start cpurc or termrc scripts from mounted root [cpu terminal]
staylocal - whether to stay within the namespace of the plan9rc script
on the console, only option is [yes] afterfact - command to execute
after starting factotum (happens before everything else) afterroot -
command to execute after mounting rootfs but before initscript or cpu
or termrc

options for ramskel and initksel can also be set in plan9.ini

tgzfs= specifies a compressed fs to retrive from 9fat for extra files.
set to tools.tgz to use the provided example binddevs=no turns off
binding off default kernel devices hostfactotum=no turns off putting a
default password into bootes factotum netsvc=no turns off ipconfig
cpusvc=no turns off cpu and rx service hubsvc=no turns off hubfs
cpuport=number of port for cpu to listen on hostcsdns=no starts a cs
and dns server if available in the rootless service namespace
unprivileged=no starts a keyfs and auth server if available