This directory holds the source code modifications and compiled tools
for a Plan 9 kernel that can boot with no root fileserver, and places
all the post-kernel load bootup procedures into an rc-based
environment.  The user can also choose to bypass the normal bootup
procedure entirely and create a small self-sufficient ramdisk based
cpu server.  The non-rooted cpu server environment can act as a host
or "namespace hypervisor" for multiple other plan 9 environments.  The
current toolkit is focused on standard pc bootup sequences.  Fossil,
Venti, kfs, cfs and booting from USB are all supported.  Test coverage
has been focused on fossil and venti based environments using standard
pc desktop hardware.

To use the precompiled kernel, just boot it and it will provide an
interactive environment for starting and attaching to bootup services,
or if you provide appropriate configuration variables via plan9.ini it
will follow them with results that should be mostly identical to a
standard kernel.  It provides many tools compiled into boot allowing
the kernel to be self-sufficient in starting and attaching to
services.  It is optional to provide an additional .tgz in the bootup
partition which can allow for local customization of the early boot
environment without recompiling the kernel.  There are already many
useful tools compiled right into /boot of the kernel so it is not
necessary to download the tools.tgz to use the precompiled kernel
effectively.

The core kernel remains mostly unmodified, but the traditional boot
and init programs have been combined into a single, smaller program
that aims to transfer control to rc as soon as possible.  An rc script
called "plan9rc" controls the functions of starting factotum,
potentially creating a small ramfs based independent environment,
starting venti/fossil/kfs or dialing an external fs in the fashion of
a tcp booted cpu.

By setting interactive=yes in plan9.ini the user can control whether
or not any or all of these services are started and with what
variables.  To emulate traditional boot intsead, set traditional=yes
to receive only a "root is from" prompt.  The user can also drop to an
rc shell to work freely with whatever tools are compiled into /boot or
setup in a ramfs.  The kernel was compiled as a cpu kernel, but
setting factotum=terminal and rootstart=terminal should produce
terminal-style behavior.  Interactive mode is useful for bringing new
nodes online because the configuration is saved to temporary files on
the ramdisk and may be used as a plan9.ini menuitem option.

Other plan9.ini variables can be used to control the behavior of
options additional boot time behavior.  A provided skeleton fs setup
can be controlled with the ramsetup variable, which defaults to use a
provided script, ramskel.  Another optional script can be run later in
boot.  The provided 'initskel' script (requires initscript=initskel
option) starts a minimal cpu server environement in the restricted
initial namespace.  The default port for this is 17020 to avoid
conflict with a standard cpu listener started later.

It is possible to create multiple independent environments with the
kernel-rooted environment separate from any of them.  With suitable
control of options, the plan9rc script can be used as a general
purpose launcher for plan 9 environments.  Also, it is possible to
provide a separate key at boot time for the early boot environment,
but this runs the risk of conflicting with existing auth servers and
requires some understanding of factotum namespaces to make use of.

There are also some scripts that provide easy ways to modify your
namespace to acquire different "roots".  Especially useful is
"rerootwin [target]" which accepts the name of a /srv or an ip or
system name to dial and arranges to use it as the root of the
environment while still keeping the devices from /mnt/term in the
namespace.  addwrroot and addroroot attach to the target in writable
or read-only mode without the extra shenanigans.  addsources gives you
access to sources copy of the distribution as your 'root'.  Another
package of scripts assists in saving fossil rootscores and resetting
fossils to known states.  These can be used to rapidly transfer the
root of your active environment to different hardware.

Other scripts included are some for rapidly cloning fossils across the
network using their rootscore.  The cpsys script calls one machine,
gets its most recent rootscore, then calls anothe rmachine and tells
it to stop its local fossil and reset it to the given score.  This can
be used to rapidly shift your physical hardware dependency on a given
fileserver while still maintaining access to data.  Another helper
script assists with progressive backup of venti data.

To install without recompiling, place the 9pcram.gz kernel in your
9fat: partition and edit plan9.ini to use a boot menu to give you the
option of using that kernel.  Some additional tweaking and studying of
what is going on is recommended for effective use.  The precompiled
kernel also includes the writable /proc/ns mod which is the basis for
the cpns, addns, subns process namespace manipulation scripts.

Please view doc/ants.ps for the full Giants ANTS paper.

This kernel version and software originally based on the Plan 9 source
tree from December of 2009.  Development resumed with updated plan 9
sources in January 2013. Updated in July 2015.

These tools include code from the main Plan 9 distribution. Original portions
copyright Mycroftiv. Licensed under the Lucent Public License.