[bootlin/training-materials updates] master: U-Boot slides: clarify environment explanations (b173e5f5)
Michael Opdenacker
michael.opdenacker at bootlin.com
Thu Sep 24 14:03:11 CEST 2020
Repository : https://github.com/bootlin/training-materials
On branch : master
Link : https://github.com/bootlin/training-materials/commit/b173e5f5b4cf9069bd65d3647c76abf5ae434878
>---------------------------------------------------------------
commit b173e5f5b4cf9069bd65d3647c76abf5ae434878
Author: Michael Opdenacker <michael.opdenacker at bootlin.com>
Date: Thu Sep 24 14:03:11 2020 +0200
U-Boot slides: clarify environment explanations
Signed-off-by: Michael Opdenacker <michael.opdenacker at bootlin.com>
>---------------------------------------------------------------
b173e5f5b4cf9069bd65d3647c76abf5ae434878
.../sysdev-bootloaders-u-boot.tex | 44 ++++++++++++++-------
.../u-boot-environment-configuration.png | Bin 0 -> 131462 bytes
2 files changed, 29 insertions(+), 15 deletions(-)
diff --git a/slides/sysdev-bootloaders-u-boot/sysdev-bootloaders-u-boot.tex b/slides/sysdev-bootloaders-u-boot/sysdev-bootloaders-u-boot.tex
index b4775923..1e8a0b13 100644
--- a/slides/sysdev-bootloaders-u-boot/sysdev-bootloaders-u-boot.tex
+++ b/slides/sysdev-bootloaders-u-boot/sysdev-bootloaders-u-boot.tex
@@ -217,15 +217,16 @@ GNU ld (crosstool-NG 1.24.0.105_5659366) 2.34
\item \code{fatload}, loads a file from a FAT filesystem to RAM
\begin{itemize}
\item Example: \code{fatload usb 0:1 0x21000000 zImage}
- \item And also \code{fatls} and \code{fatinfo}
+ \item And also \code{fatinfo}, \code{fatls}, \code{fatsize},
+ \code{fatwrite}...
\end{itemize}
\item \code{ext2load}, loads a file from an ext2 filesystem to RAM
\begin{itemize}
- \item And also \code{ext2ls} to list files, \code{ext2info} for
- information
+ \item And also \code{ext2info}, \code{ext2ls}, \code{ext2size},
+ \code{ext2write}...
\end{itemize}
\item Similar commands for other filesystems: \code{ext4load},
- \code{ext4ls}, \code{sqfsload}, \code{sqfsls}
+ \code{ext4ls}, \code{sqfsload}, \code{sqfsls}...
(\href{https://bootlin.com/blog/bootlin-contributes-squashfs-support-to-u-boot/}{SquashFS
support contributed by Bootlin})...
\item \code{tftp}, loads a file from the network to RAM (example given later)
@@ -263,19 +264,32 @@ GNU ld (crosstool-NG 1.24.0.105_5659366) 2.34
\begin{frame}
\frametitle{Environment variables: principle}
- \begin{itemize}
- \item U-Boot can be configured through environment variables
+ \begin{columns}
+ \column{0.7\textwidth}
\begin{itemize}
- \item Some specific environment variables affect the behavior of
- the different commands
- \item Custom environment variables can be added, and used in
- scripts
+ \item U-Boot can be configured through environment variables
+ \begin{itemize}
+ \item Some specific environment variables impact the behavior of
+ the different commands
+ \item Custom environment variables can be added, and used in
+ scripts
+ \end{itemize}
+ \item Environment variables are loaded from persistent storage to RAM at U-Boot
+ startup. They can be defined or modified and saved back to storage for persistence
+ \item Depending on the configuration, the U-Boot environment is typically stored in:
+ \begin{itemize}
+ \item At a fixed offset in NAND flash
+ \item At a fixed offset on MMC or USB storage, before the beginning of
+ the first partition.
+ \item In a file (\code{uboot.env}) on a FAT or ext4 partition
+ \item In a UBI volume
+ \end{itemize}
\end{itemize}
- \item Environment variables are loaded from flash to RAM at U-Boot
- startup. They can be defined or modified and saved back to flash for persistence
- \item There is a dedicated location in flash (or in MMC storage)
- to store the U-Boot environment, defined in the board configuration file
- \end{itemize}
+ \column{0.3\textwidth}
+ \includegraphics[width=\textwidth]{slides/sysdev-bootloaders-u-boot/u-boot-environment-configuration.png}\\
+ \vspace{0.3cm}
+ \tiny U-Boot environment configuration menu
+ \end{columns}
\end{frame}
\begin{frame}
diff --git a/slides/sysdev-bootloaders-u-boot/u-boot-environment-configuration.png b/slides/sysdev-bootloaders-u-boot/u-boot-environment-configuration.png
new file mode 100644
index 00000000..93271389
Binary files /dev/null and b/slides/sysdev-bootloaders-u-boot/u-boot-environment-configuration.png differ
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