Document some relevant cmdline options

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

docs/Makefile.am

@@ -1,4 +1,4 @@
 docsdir   := @docdir@/docs
 docs_DATA  = config.md conditions.md distro.md inetd.md plugins.md	\
-	     service.md signals.md svc-machine.png
+	     service.md signals.md svc-machine.png cmdline.md
 EXTRA_DIST = $(docs_DATA)

docs/cmdline.md

@@ -0,0 +1,38 @@
+Tips & Tricks with the kernel cmdline
+=====================================
+
+This document summarizes the different boot parameters that can be
+passed on the Linux kernel command line.  Not just limited to Finit.
+
+* `debug`, or `--debug`  
+    Enable debug mode.  The former syntax also enable kernel debug, and
+    the latter only in Finit.  Debug messages are printed to the console
+    until a syslog daemon has been started.
+
+* `init=/bin/sh`  
+    Bypass system default init and tell kernel to start a shell.  Note,
+	this shell is very limited and does not support signals and has no
+	job control.  Recommend using, and modifying, `rescue` mode instead.
+
+* `panic=SEC`  
+    By default the kernel does not reboot after a kernel panic.  This
+    setting will cause a kernel reboot after SEC seconds.
+
+* `quiet`  
+    Suppress kernel logging to console, except for warnings and errors.
+
+* `rescue`  
+    Start Finit rescue mode; no network, no `fsck` of file systems in
+    `/etc/fstab`, no `/etc/rc.local`, no `runparts`.  The configuration
+    is read from `/etc/rescue.conf`, can be modified by the operator.
+
+* `single`, or `S`  
+    Single user mode, runlevel 1, in Finit.  Useful to debug problems with
+    the regular runlevel.  All services and TTYs in `[1]` will be started,
+    so a `tty [1] @console nologin` configuration presents you with a
+    root console without login.
+
+* `splash`  
+    Display Finit splash screen with progress at bootstrap and shutdown.
+
+For more on kernel boot paramaters, see the man page `bootparam(7)`.