Break out building and bootstrap to separate files

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

doc/bootstrap.md

@@ -0,0 +1,52 @@
+Bootstrap
+=========
+
+1. Populate `/dev`
+2. Parse `/etc/finit.conf`
+3. Load all `.so` plugins
+4. Remount/Pivot `/` to get R+W
+5. Call 1st level hooks, `HOOK_ROOTFS_UP`
+6. Mount `/etc/fstab` and swap, if available
+7. Cleanup stale files from `/tmp/*` et al
+8. Enable SysV init signals
+9. Call 2nd level hooks, `HOOK_BASEFS_UP`
+10. Start all 'S' runlevel tasks and services
+11. Load kernel parameters from `/etc/sysctl.conf`
+12. Set hostname and bring up loopback interface
+13. Call `network` script, if set in `/etc/finit.conf`
+14. Call 3rd level hooks, `HOOK_NETWORK_UP`
+15. Switch to the configured runlevel from `/etc/finit.conf`, default 2.
+    At every runlevel change all `*.conf` files in `/etc/finit.d/` are
+    (re)loaded and new services, tasks, and blocking run commands are
+    started.  Provided they are allowed in the new runlevel and all of
+    their conditions, if any, are set.
+16. Call 4th level hooks, `HOOK_SVC_UP`
+17. If `runparts <DIR>` is set, [run-parts(8)][] is called on `<DIR>`
+18. Call `/etc/rc.local`, if it exists and is an executable shell script
+19. Call 5th level (last) hooks, `HOOK_SYSTEM_UP`
+20. Start TTYs defined in `/etc/finit.conf`, or rescue on `/dev/console`
+
+In (10) and (15) tasks and services defined in `/etc/finit.conf` are
+started.  Remember, all `service` and `task` stanzas are started in
+parallel and `run` in sequence, and in the order listed.  Hence, to
+emulate a SysV `/etc/init.d/rcS` one could write a long file with only
+`run` statements.
+
+Notice the five hook points that are called at various point in the
+bootstrap process.  This is where plugins can extend the boot in any way
+they please.
+
+For instance, at `HOOK_BASEFS_UP` a plugin could read an XML file from a
+USB stick, convert/copy its contents to the system's `/etc/` directory,
+well before all 'S' runlevel tasks are started.  This could be used with
+system images that are created read-only and all configuration is stored
+on external media.
+
+
+[run-parts(8)]: http://manpages.debian.org/cgi-bin/man.cgi?query=run-parts
+
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