user-doc: document important requirements for building the kernel and initramfs

master
S.J.R. van Schaik 7 years ago
parent 78fbe03b20
commit 6e11e9079d
  1. 18
      user-doc/user-doc.tex

@ -126,10 +126,26 @@ After the configuration options have been set up, rebuild the u-boot binary agai
\subsection{Linux kernel}
{\tt CONFIG\_KEXEC}
Make sure that the following options are enabled:
\begin{itemize}[noitemsep]
\item {\tt CONFIG\_BLK\_DEV\_INITRD}
\item {\tt CONFIG\_RD\_GZIP}
\item {\tt CONFIG\_RD\_BZIP2}
\item {\tt CONFIG\_RD\_LZMA}
\item {\tt CONFIG\_RD\_XZ}
\item {\tt CONFIG\_RD\_LZO}
\item {\tt CONFIG\_RD\_LZ4}
\item {\tt CONFIG\_KEXEC}
\end{itemize}
As the ROTS image will be read-only once it has been flashed to the SPI NOR flash, it is encouraged to build a minimal kernel images to reduce the amount of possible bugs and vulnerabilities.
More specifically, it is recommended to build a kernel without any support for networking, graphics and audio.
\subsection{initramfs}
For the initramfs, we will need static binaries of \emph{busybox}, \emph{kexec-tools}, \emph{cpio} and \emph{gzip}.
\section{Flashing ROTS}
\subsection{Using an External Programmer}

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