slides/yocto-image: misc details and improvements

Signed-off-by: Michael Opdenacker <[email protected]>

slides/yocto-image/yocto-image.tex

@@ -51,12 +51,13 @@ \subsection{Introduction to images}
         \item \yoctovar{IMAGE_BASENAME}: The name of the output image files.
           Defaults to \code{${PN}}.
         \item \yoctovar{IMAGE_INSTALL}: List of packages and package groups to
-          install in the generated image.
+          install in the generated image (only toplevel packages, dependencies unnecessary)
         \item \yoctovar{IMAGE_ROOTFS_SIZE}: The final root filesystem size.
         \item \yoctovar{IMAGE_FEATURES}: List of features to enable in the
-          image.
+          image (e.g. \code{allow-root-login}).
         \item \yoctovar{IMAGE_FSTYPES}: List of formats the OpenEmbedded build
-          system will use to create images.
+          system will use to create images. Could be set in machine
+          definitions too (machine dependent).
         \item \yoctovar{IMAGE_LINGUAS}: List of the locales to be supported in
           the image.
         \item \yoctovar{IMAGE_PKGTYPE}: Package type used by the build system.
@@ -80,6 +81,8 @@ \subsection{Introduction to images}
 IMAGE_INSTALL += "ninvaders"
     \end{minted}
   \end{block}
+  Note: unlike other recipes, machine recipes don't need to set
+  \yoctovar{LICENSE}.
 \end{frame}
 
 \begin{frame}
@@ -93,7 +96,7 @@ \subsection{Introduction to images}
         \item One or more images files are created, depending on the
           \yoctovar{IMAGE_FSTYPES} value.
       \end{enumerate}
-    \item The rootfs creation is specific to the \yoctovar{IMAGE_PKGTYPE}
+    \item Root filesystem creation is specific to the \yoctovar{IMAGE_PKGTYPE}
       value. It should be defined in the image recipe, otherwise the
       first valid package type defined in \yoctovar{PACKAGE_CLASSES} is
       used.
@@ -113,8 +116,9 @@ \subsection{Image types}
     \item Image formats instructions are provided by
       \code{openembedded-core}, in
       \code{meta/classes/image_types.bbclass}
-    \item Common image formats are: ext2, ext3, ext4, squashfs,
-      squashfs-xz, cpio, jffs2, ubifs, tar.bz2, tar.gz\dots
+    \item Common image formats are: \code{ext2}, \code{ext3}, \code{ext4},
+          \code{squashfs}, \code{squashfs-xz}, \code{cpio}, \code{jffs2},
+          \code{ubifs}, \code{tar.bz2}, \code{tar.gz}\dots
   \end{itemize}
 \end{frame}
 
@@ -134,7 +138,8 @@ \subsection{Image types}
 \begin{frame}
   \frametitle{Creating an image conversion type}
   \begin{itemize}
-    \item Common conversion types are: gz, bz2, sha256sum, bmap\dots
+    \item Common conversion types are: \code{gz}, \code{bz2},
+          \code{sha256sum}, \code{bmap}\dots
     \item This is done through a class that inherits from
       \code{image_types}.
     \item It has to define a function named \yoctovar{CONVERSION_CMD}\code{:<type>}.
@@ -148,7 +153,8 @@ \subsection{Image types}
   \begin{itemize}
     \item \code{wic} is a tool that can create a flashable image from
       the compiled packages and artifacts.
-    \item It can create partitions.
+    \item It can create partitions (but doesn't support raw flash partitions
+          and filesystems)
     \item It can select which files are located in
       which partition through the use of plugins.
     \item The final image layout is described in a \code{.wks} or
@@ -161,6 +167,8 @@ \subsection{Image types}
 IMAGE_FSTYPES = "wic.bmap wic"
         \end{minted}
       \end{block}
+    \item Note: \code{bmaptool} is an alternative to \code{dd},
+      skipping uninitialized contents in partitions.
   \end{itemize}
 \end{frame}