[FE training-materials-updates] buildroot-build: new slide chapter
Thomas Petazzoni
thomas.petazzoni at free-electrons.com
Thu Apr 30 16:57:08 CEST 2015
Repository : git://git.free-electrons.com/training-materials.git
On branch : master
Link : http://git.free-electrons.com/training-materials/commit/?id=9472ccd2f300f5f65048b116f98960522e2049ef
>---------------------------------------------------------------
commit 9472ccd2f300f5f65048b116f98960522e2049ef
Author: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
Date: Thu Apr 30 14:44:26 2015 +0200
buildroot-build: new slide chapter
Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
>---------------------------------------------------------------
9472ccd2f300f5f65048b116f98960522e2049ef
Makefile | 1 +
slides/buildroot-build/buildroot-build.tex | 307 +++++++++++++++++++++++++++++
2 files changed, 308 insertions(+)
diff --git a/Makefile b/Makefile
index 7b1c925..6a752f9 100644
--- a/Makefile
+++ b/Makefile
@@ -286,6 +286,7 @@ BUILDROOT_SLIDES = \
course-information \
setup-lab \
buildroot-introduction \
+ buildroot-build \
buildroot-tree \
buildroot-toolchain \
buildroot-rootfs \
diff --git a/slides/buildroot-build/buildroot-build.tex b/slides/buildroot-build/buildroot-build.tex
new file mode 100644
index 0000000..f2b4d1a
--- /dev/null
+++ b/slides/buildroot-build/buildroot-build.tex
@@ -0,0 +1,307 @@
+\section{Managing the build and the configuration}
+
+\begin{frame}{Default build organization}
+ \begin{itemize}
+ \item By default:
+ \begin{itemize}
+ \item All the build output goes into a directory called
+ \code{output/} within the top-level Buildroot source directory.
+ \begin{itemize}
+ \item \code{O = output}
+ \end{itemize}
+ \item The configuration file is stored as \code{.config} in the
+ top-level Buildroot source directory.
+ \begin{itemize}
+ \item \code{CONFIG_DIR = $(TOPDIR)}
+ \item \code{TOPDIR = $(shell pwd)}
+ \end{itemize}
+ \item \code{buildroot/}
+ \begin{itemize}
+ \item {\bf \code{.config}}
+ \item \code{arch/}
+ \item \code{package/}
+ \item {\bf \code{output/}}
+ \item \code{fs/}
+ \item ...
+ \end{itemize}
+ \end{itemize}
+ \end{itemize}
+\end{frame}
+
+\begin{frame}{Out of tree build: introduction}
+ \begin{itemize}
+ \item Out of tree build allows to use an output directory different
+ than \code{output/}
+ \item Useful to build different Buildroot configurations with the
+ same source tree.
+ \item Customization of the output directory done by passing
+ \code{O=/path/to/directory} on the command line.
+ \item Configuration file stored inside the \code{$(O)} directory, as
+ opposed to inside the Buildroot sources for the in-tree build
+ case.
+ \item \code{project/}
+ \begin{itemize}
+ \item \code{buildroot/}, Buildroot sources
+ \item \code{foo-output/}, output of a first project
+ \begin{itemize}
+ \item \code{.config}
+ \end{itemize}
+ \item \code{bar-output/}, output of a second project
+ \begin{itemize}
+ \item \code{.config}
+ \end{itemize}
+ \end{itemize}
+ \end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]{Out of tree build: using}
+ \begin{itemize}
+ \item To start an out of tree build, two solutions:
+ \begin{itemize}
+ \item From the Buildroot source tree, simplify specify a \code{O=}
+ variable:
+ \begin{block}{}
+\begin{verbatim}
+make O=../foo-output/ menuconfig
+\end{verbatim}
+ \end{block}
+ \item From an empty output directory, specify \code{O=} and the
+ path to the Buildroot source tree:
+ \begin{block}{}
+\begin{verbatim}
+make -C ../buildroot/ O=$(pwd) menuconfig
+\end{verbatim}
+ \end{block}
+ \end{itemize}
+ \item Once one out of tree operation has been done
+ (\code{menuconfig}, loading a defconfig, etc.), Buildroot creates
+ a small wrapper \code{Makefile} in the output directory.
+ \item This wrapper \code{Makefile} then avoids the need to pass
+ \code{O=} and the path to the Buildroot source tree.
+ \end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]{Out of tree build: example}
+ \small
+ \begin{enumerate}
+ \item You are in your Buildroot source tree:\\
+{\tiny
+\begin{block}{}
+\begin{verbatim}
+$ ls
+arch board boot ... Makefile ... package ...
+\end{verbatim}
+\end{block}
+}
+ \item Create a new output directory, and move to it:\\
+{\tiny
+\begin{block}{}
+\begin{verbatim}
+$ mkdir ../foobar-output
+$ cd ../foobar-output
+\end{verbatim}
+\end{block}
+}
+ \item Start a new Buildroot configuration:\\
+{\tiny
+\begin{block}{}
+\begin{verbatim}
+$ make -C ../buildroot O=$(pwd) menuconfig
+\end{verbatim}
+\end{block}
+}
+ \item Start the build (passing \code{O=} and \code{-C} no longer needed thanks to the wrapper):\\
+{\tiny
+\begin{block}{}
+\begin{verbatim}
+$ make
+\end{verbatim}
+\end{block}
+}
+ \item Adjust the configuration again, restart the build, clean the build:\\
+{\tiny
+\begin{block}{}
+\begin{verbatim}
+$ make menuconfig
+$ make
+$ make clean
+\end{verbatim}
+\end{block}
+}
+ \end{enumerate}
+\end{frame}
+
+\begin{frame}{Full config file vs. {\em defconfig}}
+ \begin{itemize}
+ \item The \code{.config} file is a {\em full} config file: it
+ contains the value for all options (except those having unmet
+ dependencies)
+ \item The default \code{.config}, without any customization, has
+ 2618 lines (as of Buildroot 2015.02)
+ \begin{itemize}
+ \item Not very practical for reading and modifying by humans.
+ \end{itemize}
+ \item A {\em defconfig} stores only the values for options for which
+ the non-default value is chosen.
+ \begin{itemize}
+ \item Much easier to read
+ \item Can be modified by humans
+ \item Can be used for automated construction of configurations
+ \end{itemize}
+ \end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]{{\em defconfig}: example}
+ \begin{itemize}
+ \item For the default Buildroot configuration, the {\em defconfig}
+ is empty: everything is the default.
+ \item If you change the architecture to be ARM, the {\em defconfig}
+ is just one line:
+{\small
+\begin{block}{}
+\begin{verbatim}
+BR2_arm=y
+\end{verbatim}
+\end{block}
+}
+ \item If then you also enable the \code{stress} package, the {\em
+ defconfig} will be just two lines:
+{\small
+\begin{block}{}
+\begin{verbatim}
+BR2_arm=y
+BR2_PACKAGE_STRESS=y
+\end{verbatim}
+\end{block}
+}
+ \end{itemize}
+\end{frame}
+
+\begin{frame}{Using and creating a {\em defconfig}}
+ \begin{itemize}
+ \item To use a {\em defconfig}, copying it to \code{.config} is not
+ sufficient as all the missing (default) options need to be
+ expanded.
+ \item Buildroot allows to load {\em defconfig} stored in the
+ \code{configs/} directory, by doing:
+ \code{make <foo>_defconfig}
+ \begin{itemize}
+ \item It overwrites the current \code{.config}, if any
+ \end{itemize}
+ \item To create a {\em defconfig}, run:\\
+ \code{make savedefconfig}
+ \begin{itemize}
+ \item By default, saved as \code{defconfig}.
+ \item Can be customized using \code{BR2_DEFCONFIG} configuration
+ option (can also be passed in the environment)
+ \end{itemize}
+ \end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]{Assembling a {\em defconfig} (1/2)}
+
+ \begin{itemize}
+ \item {\em defconfigs} are trivial text files, one can use simple
+ concatenation to assemble them from fragments.
+ \end{itemize}
+
+{\small
+ \begin{block}{platform1.frag}
+\begin{verbatim}
+BR2_arm=y
+BR2_TOOLCHAIN_BUILDROOT_WCHAR=y
+BR2_GCC_VERSION_4_9_X=y
+\end{verbatim}
+ \end{block}
+}
+
+{\small
+ \begin{block}{platform2.frag}
+\begin{verbatim}
+BR2_mipsel=y
+BR2_TOOLCHAIN_EXTERNAL=y
+BR2_TOOLCHAIN_EXTERNAL_CODESOURCERY_MIPS201405=y
+\end{verbatim}
+ \end{block}
+}
+
+{\small
+ \begin{block}{packages.frag}
+\begin{verbatim}
+BR2_PACKAGE_STRESS=y
+BR2_PACKAGE_MTD=y
+BR2_PACKAGE_LIBCONFIG=y
+\end{verbatim}
+ \end{block}
+}
+
+\end{frame}
+
+\begin{frame}[fragile]{Assembling a {\em defconfig} (1/2)}
+
+{\small
+ \begin{block}{debug.frag}
+\begin{verbatim}
+BR2_ENABLE_DEBUG=y
+BR2_PACKAGE_STRACE=y
+\end{verbatim}
+ \end{block}
+}
+
+\begin{itemize}
+
+ \item Build a release system for {\em platform1}:
+{\small
+ \begin{block}{}
+\begin{verbatim}
+$ cat platform1.frag packages.frag > configs/foo_defconfig
+$ make foo_defconfig && make
+\end{verbatim}
+ \end{block}{}
+}
+ \item Build a debug system for {\em platform2}:
+{\small
+ \begin{block}{}
+\begin{verbatim}
+$ cat platform2.frag packages.frag debug.frag > \
+ configs/foo_defconfig
+$ make foo_defconfig && make
+\end{verbatim}
+ \end{block}
+}
+
+\end{itemize}
+
+\end{frame}
+
+\begin{frame}[fragile]{Other building tips}
+ \begin{itemize}
+ \item Cleaning targets
+ \begin{itemize}
+ \item Cleaning all the build output, but keeping the configuration
+ file:
+ \begin{block}{}
+\begin{verbatim}
+$ make clean
+\end{verbatim}
+ \end{block}
+ \item Cleaning everything, including the configuration file:
+ \begin{block}{}
+\begin{verbatim}
+$ make distclean
+\end{verbatim}
+ \end{block}
+ \end{itemize}
+ \item Verbose build
+ \begin{itemize}
+ \item By default, Buildroot hides a number of commands it runs
+ during the build, only showing the most important ones.
+ \item To get a fully verbose build, pass \code{V=1}:
+ \begin{block}{}
+\begin{verbatim}
+$ make V=1
+\end{verbatim}
+ \end{block}
+ \end{itemize}
+ \end{itemize}
+\end{frame}
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