This describes how to setup and use an OpenEmbedded build environment with Yocto including the Linaro layer and a layer that includes a Device Tree kernel specific to Versatile Express boards and models.
The meta-linaro layer focuses on toolchain components and employs recipes for building the Linaro GCC the OE way.
For builds with "master" branch of OpenEmbedded Core some more work is needed due to gcc-4.6 being removed from it (described later).
Please refer to the Yocto Quick Start and the Linaro on OpenEmbedded wiki page for any issues.
- Prepare build environment =========================
Packages and package installation vary depending on your development system. In general, you need to have root access and then install the required packages. The next few sections show you how to get set up with the right packages for Ubuntu, Fedora, openSUSE, and CentOS.
The packages you need for a supported Ubuntu distribution are shown in the following command:
$ sudo apt-get install sed wget subversion git-core coreutils \
unzip texi2html texinfo libsdl1.2-dev docbook-utils fop gawk \
python-pysqlite2 diffstat make gcc build-essential xsltproc \
g++ desktop-file-utils chrpath libgl1-mesa-dev libglu1-mesa-dev \
autoconf automake groff libtool xterm libxml-parser-perl
The packages you need for a supported Fedora distribution are shown in the following commands:
$ sudo yum groupinstall "development tools"
$ sudo yum install python m4 make wget curl ftp tar bzip2 gzip \
unzip perl texinfo texi2html diffstat openjade \
docbook-style-dsssl sed docbook-style-xsl docbook-dtds fop xsltproc \
docbook-utils sed bc eglibc-devel ccache pcre pcre-devel quilt \
groff linuxdoc-tools patch cmake \
perl-ExtUtils-MakeMaker tcl-devel gettext chrpath ncurses apr \
SDL-devel mesa-libGL-devel mesa-libGLU-devel gnome-doc-utils \
autoconf automake libtool xterm
The packages you need for a supported openSUSE distribution are shown in the following command:
$ sudo zypper install python gcc gcc-c++ libtool fop \
subversion git chrpath automake make wget xsltproc \
diffstat texinfo freeglut-devel libSDL-devel
The packages you need for a supported CentOS distribution are shown in the following commands:
$ sudo yum -y groupinstall "development tools"
$ sudo yum -y install tetex gawk sqlite-devel vim-common redhat-lsb xz \
m4 make wget curl ftp tar bzip2 gzip python-devel \
unzip perl texinfo texi2html diffstat openjade zlib-devel \
docbook-style-dsssl sed docbook-style-xsl docbook-dtds \
docbook-utils bc glibc-devel pcre pcre-devel \
groff linuxdoc-tools patch cmake \
tcl-devel gettext ncurses apr \
SDL-devel mesa-libGL-devel mesa-libGLU-devel gnome-doc-utils \
autoconf automake libtool xterm
There are two branches that can be used: Master, which is the latest code; Denzil, which is the latest official release from the Yocto project. Decide which branch you wish to use and follow the steps according to you branch choice.
mkdir oe && cd oe
git clone git://git.linaro.org/openembedded/meta-linaro.git
git clone git://git.openembedded.org/openembedded-core
git clone git://github.com/awafaa/meta-vexa15.git
cd openembedded-core
git clone git://git.openembedded.org/bitbake bitbake
cd .. && git clone git://git.openembedded.org/meta-openembedded
rm meta-linaro/recipes-lamp/mysql/*
cd meta-linaro
git checkout -b 4.7-2012.06 4.7-2012.06
cd ..
cd openembedded-core
git checkout -b 363424c 363424c
cd bitbake
git checkout -b f8bf449 f8bf449
cd ..
Most of the patches to OE Core that are required for the meta-linaro are upstream already. Currently there is only one optional patch that removes the -no-tree-vectorize GCC option for armv7a machines.
cd openembedded-core
wget -q -O - http://people.linaro.org/~kwerner/oe-core/patches/armv7a-tree-vectorize.patch | patch -p1
- Setup the environment ========================
The next step is to create the build directory and setting up an appropriate configuration.
. ./oe-init-build-env ../build
Add the Linaro and kernel meta layer by editing the conf/bblayers.conf. The BBLAYERS variable should look like this:
BBLAYERS = " \
${TOPDIR}/../meta-vexa15 \
${TOPDIR}/../meta-linaro \
${TOPDIR}/../meta-openembedded/toolchain-layer \
${TOPDIR}/../openembedded-core/meta"
BBLAYERS = " \
${TOPDIR}/../meta-vexa15 \
${TOPDIR}/../meta-linaro \
${TOPDIR}/../openembedded-core/meta"
# set the default machine and target
MACHINE = "qemuarmv7a"
DEFAULTTUNE_qemuarmv7a = "armv7athf-neon"
# specify the alignment of the root file system
# this is required when building for qemuarmv7a
IMAGE_ROOTFS_ALIGNMENT = "2048"
Also alter the following variables depending on your build machine:
BB_NUMBER_THREADS
PARALLEL_MAKE
What values should one use? BB_NUMBER_THREADS controls how many tasks are run at same time and "4" is a reasonable amount. Generally speaking change the values to be twice the number of CPUs that your machine has.
By default the toolchain provided by OE Core gets used. In order to build using the Linaro GCC the following lines needs to be added:
# Use Linaro's GCC
GCCVERSION = "linaro-4.7"
SDKGCCVERSION = "linaro-4.7"
The choices are:
-
'4.6%' - GCC 4.6 based toolchain provided by OE Core (denzil) or OpenEmbedded (master)
-
'4.7%' - GCC 4.7 based toolchain provided by OE Core
-
'linaro-4.6' - Linaro GCC 4.6 based toolchain provided by meta-linaro
-
'linaro-4.7' - Linaro GCC 4.7 based toolchain provided by meta-linaro
The meta-vexa15 layer provides two kernels, an upstream mainline kernel and an AEL 3.3 kernel. To specify which one is used the following line needs to be added:
PREFERRED_PROVIDER_virtual/kernel = "linux-ael"
\
The choices are:
-
'linux-ael' – AEL 3.3 kernel
-
'linux-upstream' – Upstream mainline kernel
- Build the images ===================
First, bitbake will build some native tools like m4, autoconf, libtool and install them into a sysroot. The tools of the sysroot and the binary toolchain are used to compile the sources for the target including a Linaro 3.x based Linux kernel configured for the versatile express board. It all gets packaged up (ipk by default) and installed into a root fs.
# just enough to get a busybox prompt
bitbake core-image-minimal
# Xorg, gtk+2
bitbake core-image-sato
# Qt 4 embedded
bitbake qt4e-demo-image
The images will be created in:
# the image output lands at:
ls -l tmp-eglibc/deploy/images/
# kernel:
ls -l tmp-eglibc/deploy/images/zImage-qemuarmv7a.bin
# fs image:
ls -l tmp-eglibc/deploy/images/*-qemuarmv7a.ext3
- Using images ===============
As part of the OE Core build process qemu will be compiled. There is a wrapper script called runqemu that can be used to run the default OE Core images. Since we added a new qemuarmv7a MACHINE the runqemu script wouldn't work for us. However, we can easily run qemu manually:
- minimal image
tmp-eglibc/sysroots/x86_64-linux/usr/bin/qemu-system-arm \
-M vexpress-a9 -m 1024 -serial stdio -display none \
-snapshot -no-reboot \
-kernel tmp-eglibc/deploy/images/zImage-qemuarmv7a.bin \
-drive file=tmp-eglibc/deploy/images/core-image-minimal-qemuarmv7a.ext3,if=sd,cache=writeback \
--append "rw console=ttyAMA0,38400n8 console=tty root=/dev/mmcblk0"
- sato image
tmp-eglibc/sysroots/x86_64-linux/usr/bin/qemu-system-arm \
-M vexpress-a9 -m 1024 -serial stdio \
-snapshot -no-reboot -show-cursor \
-kernel tmp-eglibc/deploy/images/zImage-qemuarmv7a.bin \
-drive file=tmp-eglibc/deploy/images/core-image-sato-qemuarmv7a.ext3,if=sd,cache=writeback \
--append "rw console=ttyAMA0,38400n8 console=tty root=/dev/mmcblk0"
- Qt4e image
tmp-eglibc/sysroots/x86_64-linux/usr/bin/qemu-system-arm \
-M vexpress-a9 -m 1024 -serial stdio \
-snapshot -no-reboot \
-kernel tmp-eglibc/deploy/images/zImage-qemuarmv7a.bin \
-drive file=tmp-eglibc/deploy/images/qt4e-demo-image-qemuarmv7a.ext3,if=sd,cache=writeback \
--append "rw console=ttyAMA0,38400n8 console=tty root=/dev/mmcblk0"
W.I.P.
W.I.P.
- Clean up ===============
bitbake -ccleansstate world
If you want to remove everything you can use
rm -rf sstate-cache tmp* pseudodone
\