Boot time: minor init improvements

Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>

slides/boot-time-init-scripts/boot-time-init-scripts.tex

@@ -92,9 +92,11 @@ \section{Optimizing init scripts and system startup}
 	\item \code{init} scripts run in alphanumeric order and start with
 	      a letter (K for stop ({\bf k}ill) and S for {\bf s}tart).
 	\item You want to use the lowest number you can for your application.
-	\item You can even replace \code{init} with your application!
+	\item You can even replace \code{init} with your application!\\
+	      However, that's easier to keep a standard \code{init}, which also
+	      acts as a universal parent to orphan processes (otherwise
+	      you get zombies), and also takes care of implementing system shutdown.
 \end{itemize}
-How fast would we be if we could be the first started application?
 \end{frame}
 
 \begin{frame}[fragile]
@@ -104,7 +106,9 @@ \section{Optimizing init scripts and system startup}
 	      script (e.g. \code{/etc/init.d/rcS}). This eliminates multiple
 	      calls to \code{/bin/sh}.
 	\item An easier to maintain solution allowing to keep subscripts: \code{source} them\\
-              (\code{.} command) if possible. This won't spawn new shell processes.
+              (\code{.} command) if possible. This won't spawn new shell
+              processes. Buildroot's \code{/etc/init.d/rcS} file already
+              does this with \code{.sh} files.
 	\item You could mount your filesystems directly in the C code
 	      of your application:
 \end{itemize}