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+== Problem: Startup ==  #1988
+
+  Rainbow needs to be started before the first activity is started, so that it
+  can be ready to go when Sugar starts launching activities.
+
+Presently:
+
+  The startup sequence looks something like:
+
+  1. `/etc/inittab' specifies that the default runlevel is 5.
+  2. Upon entering runlevel 5, the DBus system daemon is started with priority
+     22.
+  3. `/etc/inittab' specifies that `/sbin/olpc-dm' should be started on
+     runlevel 5.
+  4. `/sbin/olpc-dm' does some basic configuration of the terminal, language
+     environment, and the session (e.g. does a PAM login); then it logs in as
+     user `olpc' and runs `startx'.
+  5. `startx' runs `xinit' which reads through /home/olpc/.xinitrc, does some
+     further graphical configuration, and then exec's `sugar'.
+  6. `sugar' is a script that uses `dbus-launch' to start the DBus session daemon.
+  7. The session daemon, once started, runs its argument `sugar-shell' with
+     appropriate environment variables.
+  8. `sugar-shell' brings up Sugar.
+
+    NB: Blizzard suggests that the current startup is hackish and should be
+        changed.
+          * In particular, we should use something less vulnerable to
+            modification than .xinitrc to start up.
+          * Also, he said that rc-scripts are going away to be replaced by a
+            monolithic start script.
+
+Plan:
+
+  In the first iteration, we will simply launch Rainbow via rc-script at a
+  higher priority than `messagebus'. Since `sugar-shell' presently records its
+  DBus session bus's address to a `session.info' file, we will simply read this
+  file to acquire access to the main DBus session bus.
+
+Followup:
+
+  Ivan suggests that we use `init' to start and respawn Rainbow.
+
+    "Creating an Unkillable Process", Silas Brown, Linux Gazette #139, 2007
+    http://linuxgazette.net/139/brownss.html
+
+  gives a nice overview of how to do this in a hardened way.
+
+  In the longer term, we may want to make the session bus talk to Rainbow in
+  some other fashion, for example by enclosing `sugar-shell' in a security stub
+  or by bringing the session bus up entirely separately from X.
+