Build your own embedded linux distributions by yocto project

Build your own Embedded
Linux distributions by
Yocto project
Yen-Chin, Lee <coldnew>
2015.08.15 中研院⼈人⽂文社會科學館 R2 10:00 ~ 10:40

• 李彥瑾 (Yen-Chin, Lee)
• GitHub: coldnew
• Gentoo Linux user
• Embedded Linux developer
• Clojure/Clojurescript developer on leisure time
About Me

• The Yocto project is an open-source collaboration project. It
provides templates, tools and methods to help you create custom
Linux-based systems for embedded products regardless of
hardware architecture.
What’s Yocto Project
It's not an embedded Linux distribution
– it creates a custom one for yout

Create Linux rootfs is hard
(1/2)
python
glibc
apt-get
busybox
xwindow mir
• Create your embedded linux roots from linux distros (TOP-DOWN)
• Remove unneeded (be careful dependency issue)
• Redo these step again when upgrade ?
bash
curl
ethtool
vim bc
what we need
what we want to remove

Create Linux rootfs is hard
(2/2)
• Create your embedded linux roots step by step (BOTTOM-UP)
• It’s like what Linux From Scratch does
• Hard to maintain
glibc
gcc
busybox xwindow
1
2
3
4 libjpeg.so
5
6
libpng.so

• BuildRoot
• OpenWrt
• ltib
• Scratchbox
• OpenEmbedded
Available system building tools

Yocto Project Overview
• Poky
• Build system used by the Yocto Project
• BitBake
• A task executor and scheduler
• Metadata
• Conﬁguration (.conf)
• global deﬁnitions of variables
• Classes (.bbclass)
• encapsulation and inheritance of build logic, packaging, etc
• Recipes (.bb)
• the logical units of software/images to build
Poky = BitBake + metadata
reference:Yocto Project Open Source Build System and Collaboration Initiative

Participating Organize
reference: https://www.yoctoproject.org/ecosystem/member-organizations

• Toaster
• web-based interface to OpenEmbedded and Bitbake
• For more info, please see Toaster Manual
What’s not cover in this slide

What’s not cover in this slide (cont’d)
• ADT (Application Development Toolkit)
• A series tools for develop with Eclipse IDE
• tracing, proﬁling, debugging
• For more info, please see Application Development Toolkit Manual

What’s not cover in this slide (cont’d)
• How to create speciﬁc machine layer
• you can use yocto-bsp command
• How to build kernel/uboot

“要學東⻄西，就要讀第⼀一⼿手資料”
– Jserv

Wandboard
(Freescale i.MX6)
SAMA5D3 Xplained
(ATMEL SAMA5D36 )
Edison
(Intel Atom Z34XX)
Books
source: google image search
beagleboard black
(TI AM335x)

Yocto Project Release
Versions
code
name
version
Release
Date
Current
Version
Support
Level
glibc/eglibc gcc
TBD 1.9
Developmen
t
glibc-2.22
5.2
4.9.3
4.8
Fido 1.8 Apr 2015 1.8 Stable glibc-2.21
4.9
4.8
Dizzy 1.7 Oct 2014 1.7.2 Stable glibc-2.20
4.9
4.8
Daisy 1.6 Apr 2014 1.6.3 Community eglibc-2.19 4.8
Dora 1.5 Oct 2013 1.5.4 Community
eglibc-2.18
eglibc-2.17
4.8
4.7
reference: https://wiki.yoctoproject.org/wiki/Releases

• Yocto support following Linux Distribution
• ubuntu
• fedora
• openSUSE
• CentOS
• debian
The Linux Distribution

Setup Environment
• Ubuntu/Debian
• CentOS
• OpenSUSE
• Fedora
sudo apt-get install gawk wget git-core diffstat unzip texinfo gcc-multilib
build-essential chrpath socat libsdl1.2-dev xterm
sudo yum install gawk make wget tar bzip2 gzip python unzip perl patch
diffutils diffstat git cpp gcc gcc-c++ glibc-devel texinfo chrpath
ccache perl-Data-Dumper perl-Text-ParseWords perl-Thread-Queue socat
findutils which SDL-devel xterm
sudo zypper install python gcc gcc-c++ git chrpath make wget python-xml
diffstat makeinfo python-curses patch socat libSDL-devel xterm
sudo yum install gawk make wget tar bzip2 gzip python unzip perl patch
diffutils diffstat git cpp gcc gcc-c++ glibc-devel texinfo chrpath
socat SDL-devel xterm

• Download poky
git clone http://git.yoctoproject.org/git/poky
cd poky
git checkout -b fido origin/fido
Getting start with Yocto
coldnew@Sara ~/poky $ tree .
.
!"" bitbake
!"" build
!"" documentation
!"" LICENSE
!"" meta
!"" meta-selftest
!"" meta-skeleton
!"" meta-yocto
!"" meta-yocto-bsp
!"" oe-init-build-env
!"" oe-init-build-env-memres
!"" README
!"" README.hardware
#"" scripts
9 directories, 5 files

• You’ll at build dir after source the oe-init-build-env
Build the minimal image for qemux86
coldnew@Sara ~/poky/build $ tree .
.
#"" conf
!"" bblayers.conf
!"" local.conf
#"" templateconf.cfg
1 directory, 3 files
• source the oe-init-build-env
coldnew@Sara ~/poky $ source oe-init-build-env
You can now run 'bitbake <target>'
Common targets are:
core-image-minimal
core-image-sato

Build the minimal image for qemux86
coldnew@Sara ~/poky/build $ bitbake core-image-minimal
WARNING: Host distribution "Gentoo" has not been validated with this version
of the build system; you may possibly experience unexpected failures. It is
recommended that you use a tested distribution.
Loading cache: 100% |##############################| ETA: 00:00:00
Loaded 1286 entries from dependency cache.
NOTE: Resolving any missing task queue dependencies
Build Configuration:
BB_VERSION = "1.26.0"
BUILD_SYS = "x86_64-linux"
NATIVELSBSTRING = "Gentoo"
TARGET_SYS = "i586-poky-linux"
MACHINE = "qemux86"
DISTRO = "poky"
DISTRO_VERSION = "1.8"
TUNE_FEATURES = "m32 i586"
TARGET_FPU = ""
meta
meta-yocto
meta-yocto-bsp = "fido:08f9fbbc97909698b56200aa9be5fe50b99a44b2"
NOTE: Preparing RunQueue
NOTE: Executing SetScene Tasks
NOTE: Executing RunQueue Tasks
Currently 3 running tasks (161 of 1989):
0: gcc-source-4.9.2-r0 do_unpack (pid 26622)

What’s in the download dir ?
coldnew@Sara ~/poky/build/downloads $ ls
alsa-lib-1.0.27.2.tar.bz2
alsa-lib-1.0.27.2.tar.bz2.done
atk-2.10.0.tar.xz
atk-2.10.0.tar.xz.done
...
bind9_9_5-CVE-2014-8500.patch.done
bind-9.9.5.tar.gz
bind-9.9.5.tar.gz.done
binfmt-install.patch.done
binutils-2.24.tar.bz2
binutils-2.24.tar.bz2.done
binutils-armv5e.patch.done
binutils_CVE-2014-8484.patch.done
coldnew@Sara ~/poky/build $ tree -L 1 .
.
!"" bitbake.lock
!"" cache
!"" conf
!"" downloads
!"" sstate-cache
#"" tmp
5 directories, 1 file

Find the generated ﬁles
coldnew@Sara ~/poky/build $ tree -L 1 .
.
!"" bitbake.lock
!"" cache
!"" conf
!"" downloads
!"" sstate-cache
#"" tmp
coldnew@Sara ~/poky/build/tmp/deploy $ tree -L 2 .
.
!"" images
$   #"" qemux86
!"" ipk
$   !"" all
$   !"" i586
$   !"" Packages
$   #"" qemux86
#"" licenses
!"" acl
!"" acl-native
!"" adwaita-icon-theme
!"" alsa-lib
...

• Execute the runqemu command
Emulation the image you build
coldnew@Sara ~/poky/build $ runqemu qemux86 core-image-minimal nographic
Assuming core-image-minimal really means ~/poky/build/tmp/deploy/images/
qemux86/core-image-minimal-qemux86.ext4
Continuing with the following parameters:
KERNEL: [~/poky/build/tmp/deploy/images/qemux86/bzImage-qemux86.bin]
ROOTFS: [~/poky/build/tmp/deploy/im
...
Poky (Yocto Project Reference Distro) 1.8+snapshot-20150813 qemux86 /dev/
ttyS0
qemux86 login: root
root@qemux86:~#
Examples:
runqemu qemuarm
runqemu qemux86-64 core-image-sato ext4
runqemu path/to/bzImage-qemux86.bin path/to/nfsrootdir/ serial
runqemu qemux86 ramfs
runqemu qemux86 iso
runqemu qemux86 qemuparams="-m 256"
runqemu qemux86 bootparams="psplash=false"
runqemu path/to/<image>-<machine>.vmdk
• More examples

$ bitbake core-image-minimal
*.conf*.conf*.conf
local.conf
bblayers.conf
…
parse
core-image-minimal.bb
reference: Poky meets Debian: Understanding How to Make an Embedded Linux by Using an Existing Distribution's Source Code
glibc.bb
busybox.bb
udev.bb
}
build
rootfs
glibc udev
busybox
build
gcc-cross.bb
binutils-cross.bb }build gcc-cross
binutils-cross
target
cross
}build
native
xxx.bbxxx.bbxxx.bb
xxxxxxxxx
depend
depend

operators
• Various operators can be used to assign values
to conﬁguration variables:
reference: Yocto project and open embedded training, p66
= expand the value then using the variable
:= immediately expand the value
+= append (with space)
=+ prepend (with space)
.= append (without space)
=. prepend (without space)
?= assign if no other value was previously assigned
??= same as previous, with a lower precedence

operators
• Avoid using +=, =+, .= and =. in conf/local.conf
• if += is parsed before ?=, the latter will be discard.
• Using _append unconditionally appends the value.
reference: Yocto project and open embedded training, p67
DISTRO_FEATURES += "x11"
DISTRO_FEATURES .= " x11” # same as above
DISTRO_FEATURES_append = " x11" # same as above

conf/local.conf
#
# Machine Selection
#
# You need to select a specific machine to target the build with. There are a selection
# of emulated machines available which can boot and run in the QEMU emulator:
#
#MACHINE ?= "qemuarm"
#MACHINE ?= "qemuarm64"
#MACHINE ?= "qemumips"
#MACHINE ?= "qemuppc"
#MACHINE ?= "qemux86"
#MACHINE ?= "qemux86-64"
#
# There are also the following hardware board target machines included for
# demonstration purposes:
#
#MACHINE ?= "beaglebone"
#MACHINE ?= "genericx86"
#MACHINE ?= "genericx86-64"
#MACHINE ?= "mpc8315e-rdb"
#MACHINE ?= "edgerouter"
#
# This sets the default machine to be qemux86 if no other machine is selected:
MACHINE ??= "qemux86"

conf/local.conf
#
# Where to place downloads
#
# During a first build the system will download many different source code tarballs
# from various upstream projects. This can take a while, particularly if your network
# connection is slow. These are all stored in DL_DIR. When wiping and rebuilding you
# can preserve this directory to speed up this part of subsequent builds. This directory
# is safe to share between multiple builds on the same machine too.
#
# The default is a downloads directory under TOPDIR which is the build directory.
#
#DL_DIR ?= "${TOPDIR}/downloads"
#
# Where to place shared-state files
#
# BitBake has the capability to accelerate builds based on previously built output.
# This is done using "shared state" files which can be thought of as cache objects
# and this option determines where those files are placed.
#
# You can wipe out TMPDIR leaving this directory intact and the build would regenerate
# from these files if no changes were made to the configuration. If changes were made
# to the configuration, only shared state files where the state was still valid would
# be used (done using checksums).
#
# The default is a sstate-cache directory under TOPDIR.
#
#SSTATE_DIR ?= "${TOPDIR}/sstate-cache"

conf/local.conf
#
# Default policy config
#
# The distribution setting controls which policy settings are used as defaults.
# The default value is fine for general Yocto project use, at least initially.
# Ultimately when creating custom policy, people will likely end up subclassing
# these defaults.
#
DISTRO ?= "poky"
# As an example of a subclass there is a "bleeding" edge policy configuration
# where many versions are set to the absolute latest code from the upstream
# source control systems. This is just mentioned here as an example, its not
# useful to most new users.
# DISTRO ?= "poky-bleeding"
#
# Package Management configuration
#
# This variable lists which packaging formats to enable. Multiple package backends
# can be enabled at once and the first item listed in the variable will be used
# to generate the root filesystems.
# Options are:
# - 'package_deb' for debian style deb files
# - 'package_ipk' for ipk files are used by opkg (a debian style embedded package manager)
# - 'package_rpm' for rpm style packages
# E.g.: PACKAGE_CLASSES ?= "package_rpm package_deb package_ipk"
# We default to rpm:
PACKAGE_CLASSES ?= "package_rpm"

conf/local.conf
#
# Extra image configuration defaults
#
# The EXTRA_IMAGE_FEATURES variable allows extra packages to be added to the generated
# images. Some of these options are added to certain image types automatically. The
# variable can contain the following options:
# "dbg-pkgs" - add -dbg packages for all installed packages
# (adds symbol information for debugging/profiling)
# "dev-pkgs" - add -dev packages for all installed packages
# (useful if you want to develop against libs in the image)
# "ptest-pkgs" - add -ptest packages for all ptest-enabled packages
# (useful if you want to run the package test suites)
# "tools-sdk" - add development tools (gcc, make, pkgconfig etc.)
# "tools-debug" - add debugging tools (gdb, strace)
# "eclipse-debug" - add Eclipse remote debugging support
# "tools-profile" - add profiling tools (oprofile, exmap, lttng, valgrind)
# "tools-testapps" - add useful testing tools (ts_print, aplay, arecord etc.)
# "debug-tweaks" - make an image suitable for development
# e.g. ssh root access has a blank password
# There are other application targets that can be used here too, see
# meta/classes/image.bbclass and meta/classes/core-image.bbclass for more details.
# We default to enabling the debugging tweaks.
EXTRA_IMAGE_FEATURES = "debug-tweaks"

conf/bblayers.conf
# LAYER_CONF_VERSION is increased each time build/conf/bblayers.conf
# changes incompatibly
LCONF_VERSION = "6"
BBPATH = "${TOPDIR}"
BBFILES ?= ""
BBLAYERS ?= "
/Yocto/poky/meta
/Yocto/poky/meta-yocto
/Yocto/poky/meta-yocto-bsp
"
BBLAYERS_NON_REMOVABLE ?= "
/Yocto/poky/meta
"

Create your own layers &
recipes

• Create your layer by yocto-layer command
• Or use yocto-bsp create <machine> <architecute> create bsp
layer
Create your own layers
coldnew@Sara ~/poky $ yocto-layer create coscup
Please enter the layer priority you'd like to use for the layer: [default: 6]
Would you like to have an example recipe created? (y/n) [default: n] n
Would you like to have an example bbappend file created? (y/n) [default: n] n
New layer created in meta-coscup.
Don't forget to add it to your BBLAYERS (for details see meta-coscupREADME).
coldnew@Sara ~/poky/meta-coscup $ tree .
.
!"" conf
$ #"" layer.conf
!"" COPYING.MIT
#"" README

• In conf/layer.conf
Create your own layers
coldnew@Sara ~/poky/meta-coscup $ tree .
.
!"" conf
$ #"" layer.conf
!"" COPYING.MIT
#"" README
# We have a conf and classes directory, add to BBPATH
BBPATH .= ":${LAYERDIR}"
# We have recipes-* directories, add to BBFILES
BBFILES += "${LAYERDIR}/recipes-*/*/*.bb
${LAYERDIR}/recipes-*/*/*.bbappend"
BBFILE_COLLECTIONS += "coscup"
BBFILE_PATTERN_coscup = "^${LAYERDIR}/"
BBFILE_PRIORITY_coscup = "6"

Layers (meta-*)
Common recipes (meta, meta-yocto, meta-yocto-bsp)
meta-qt5
BBFILE_PRIORITY_xxx
meta-fsl-arm
Override
qtbase
reference: Poky meets Debian: Understanding How to Make an Embedded Linux by Using an Existing Distribution's Source Code
5
6
7
meta-A
meta-B
meta-C
A + B + C
meta-X
X
8

Add your layer in conf/bblayers.conf
coldnew@Sara ~/poky/build $ vim conf/bblayers.conf
# LAYER_CONF_VERSION is increased each time build/conf/bblayers.conf
# changes incompatibly
LCONF_VERSION = "6"
BBPATH = "${TOPDIR}"
BBFILES ?= ""
BBLAYERS ?= "
/Yocto/poky/meta
/Yocto/poky/meta-yocto-bsp

/Yocto/poky/meta-coscup
"
BBLAYERS_NON_REMOVABLE ?= "
/Yocto/poky/meta
"
add your layers

Variables for writing recipes
(1/2)
• PN
• Package Name (ex: glibc, busybox)
• PV
• Package Version (ex: 2.11.2, 1.1.0)
• PR
• Package Revision (r0, r1, r2 …)
• WORKDIR
• Top of the build directory
• tmp/work/$ARCH/${PN}-${PV}-${PR}
• S
• Source code directory path used
by do_unpack* and do_patch*
• B
• Build directory path used by
do_conﬁgure and do_compile
• D
• Destination directory path used by
do_install
reference: Poky meets Debian: Understanding How to Make an Embedded Linux by Using an Existing Distribution's Source Code, p82
Bitbake Cheat Sheet

• ${preﬁx}
• /usr
• ${base_bindir}
• /bin
• ${base_sbindir}
• /sbin
• ${base_libdir}
• /lib
• ${datadir}
• /usr/share
• ${sysconfdir}
• /etc
• ${sbindir}
• /usr/sbin
• ${bindir}
• /usr/bin
reference: OE variable glossary
• ${libdir}
• /usr/lib
• ${includedir}
• /usr/include
Variables for writing recipes
(2/2)

bitbake Task Execution
Package A
do_fetch
do_unpack
do_patch
do_conﬁgure
do_compile
do_install
do_populate_sysroot
do_package
do_package_write_(type)
do_package_write
1 2

Example: hello_0.1.bb (1/2)
DESCRIPTION = "Simple helloworld application"
SECTION = "examples"
LICENSE = "MIT"
LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/MIT;md5=0835ade698e0bcf8506ecda2f7b4f302"
PR = "r0"
SRC_URI = "file://helloworld.c"
S = "${WORKDIR}"
do_compile() {
${CC} helloworld.c -o helloworld
}
do_install() {
install -d ${D}${bindir}
install -m 0755 helloworld ${D}${bindir}
}
coldnew@Sara ~/poky/meta-coscup $ mkdir -p recipes-example/hello
coldnew@Sara ~/poky/meta-coscup $ vim recipes-example/hello/hello_0.1.bb
coldnew@Sara ~/poky/meta-coscup/recipes-example $ tree -L 2 hello
hello/
!"" hello-0.1
$ #"" helloworld.c
#"" hello_0.1.bb

Example: hello_0.1.bb (2/2)
LICENSE = "MIT"
SRCBRANCH ??= "master"
SRCREV ?= "6f833f8b94a02511f73263bc40d605c6f4ff018b"
SRC_URI = "git://github.com/coldnew/COSCUP2015_yocto.git;protocol=ssh;branch=${SRCBRANCH}"
S = "${WORKDIR}/git/example/hello"
do_compile() {
${CC} hello.c -o hello
}
do_install() {
install -m 0755 hello ${D}${bindir}
}
tmp/deploy/ipk/i586/hello_0.1-r0.4_i586.ipk
tmp/deploy/ipk/i586/hello-dev_0.1-r0.4_i586.ipk
tmp/deploy/ipk/i586/hello-dbg_0.1-r0.4_i586.ipk

Use bbappend to add patch/modify recipes
• It’s not recommend to modify upstreams recipes directly
• use *.bbappend instead
• take hello_0.1.bb for example
coldnew@Sara ~/poky/meta-coscup/recipes-example/hello $ tree -L 2 .
.
!"" hello-0.1
$ #"" 0001-hello-coscup.patch
!"" hello_0.1.bb
#"" hello_0.1.bbappend

Use bbappend to add patch/modify recipes
(cont’d)
Index: 0.1-r0/hello.c
===================================================================
--- 0.1-r0.orig/hello.c
+++ 0.1-r0/hello.c
@@ -2,7 +2,7 @@
int main(int argc, char **argv)
{
- printf("Hello world!n");
+ printf("Hello COSCUP!n");
return 0;
}
FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}-${PV}:"
# Change "Hello World!" to "Hello COSCUP!"
SRC_URI += "file://0001-hello-coscup.patch"
• hello-0.1/0001-hello-coscup.patch
• hello-0.1/0001-hello-coscup.patch

Example: openjpeg
DESCRIPTION = "OpenJPEG library is an open-source JPEG 2000 codec"
HOMEPAGE = "http://www.openjpeg.org/index.php?menu=main"
LICENSE = "BSD"
LIC_FILES_CHKSUM = "file://LICENSE;md5=c648878b4840d7babaade1303e7f108c"
SRC_URI = "${SOURCEFORGE_MIRROR}/project/${BPN}.mirror/${PV}/${BPN}-${PV}.tar.gz"
SRC_URI[md5sum] = "f6419fcc233df84f9a81eb36633c6db6"
SRC_URI[sha256sum] = "1232bb814fd88d8ed314c94f0bfebb03de8559583a33abbe8c64ef3fc0a8ff03"
inherit cmake
DEPENDS = "libpng tiff lcms"
# standard path for *.cmake
EXTRA_OECMAKE += "-DOPENJPEG_INSTALL_PACKAGE_DIR=${baselib}/cmake
-DOPENJPEG_INSTALL_LIB_DIR:PATH=${libdir}"
FILES_${PN}-dev += "${libdir}/cmake/*.cmake"
meta-openembedded/meta-oe/recipes-graphics/openjpeg/openjpeg_2.1.0.bb

Example: hveged
SUMMARY = "haveged - A simple entropy daemon"
DESCRIPTION = “...”
HOMEPAGE = "http://www.issihosts.com/haveged/index.html"
LICENSE = "GPLv3"
LIC_FILES_CHKSUM="file://COPYING;md5=d32239bcb673463ab874e80d47fae504"
SRC_URI = "http://www.issihosts.com/haveged/haveged-${PV}.tar.gz
file://remove-systemd-unit-503.patch"
SRC_URI[md5sum] = "015ff58cd10607db0e0de60aeca2f5f8"
SRC_URI[sha256sum] = "9c2363ed9542a6784ff08e247182137e71f2ddb79e8e6c1ac4ad50d21ced3715"
inherit autotools systemd
EXTRA_OECONF = "
--enable-init=service.redhat
--enable-nistest=yes
--enable-olt=yes
--enable-threads=no "
SYSTEMD_PACKAGES = "${PN}"
SYSTEMD_SERVICE_${PN} = "haveged.service"
do_install_append() {
mkdir -p ${D}${systemd_unitdir}/system
install -p -m644 ${B}/init.d/haveged.service ${D}${systemd_unitdir}/system
}
meta-openembedded/meta-oe/recipes-extended/haveged/haveged_1.9.1.bb

Example: qtbase
# separate some parts of PACKAGECONFIG which are often changed
# be aware that you need to add icu to build qtwebkit, default
# PACKAGECONFIG is kept rather minimal for people who don't need
# stuff like webkit (and it's easier to add options than remove)
PACKAGECONFIG_GL ?= "${@base_contains('DISTRO_FEATURES', 'opengl', 'gl', '', d)}"
PACKAGECONFIG ?= "
${PACKAGECONFIG_SYSTEM}
${PACKAGECONFIG_MULTIMEDIA}
${PACKAGECONFIG_DISTRO}
"
# use either system freetype or bundled freetype, if you disable freetype completely
# fontdatabases/basic/qbasicfontdatabase.cpp will fail to build and system freetype
# works only together with fontconfig
PACKAGECONFIG[freetype] = "-system-freetype,-freetype,freetype"
PACKAGECONFIG[jpeg] = "-system-libjpeg,-no-libjpeg,jpeg"
PACKAGECONFIG[libpng] = "-system-libpng,-no-libpng,libpng"
PACKAGECONFIG[zlib] = "-system-zlib,-qt-zlib,zlib"
PACKAGECONFIG[pcre] = "-system-pcre,-qt-pcre,pcre"
meta-qt5/recipes-qt/qt5/qtbase_git.bb

Example: qtbase bbappend
FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
# Add support to accessibility, qtquickcontrol need this
PACKAGECONFIG_append = " accessibility "
# We use fontconfig (depends on glib)
PACKAGECONFIG_append = " glib fontconfig freetype "
# Use gles2 for non X11 build
PACKAGECONFIG_append = " ${@base_contains('DISTRO_FEATURES', 'x11', '', 'gles2', d)} "
# Our UI team use sqlite
PACKAGECONFIG_append = " sql-sqlite "
meta-coscup/recipes-qt/qt5/qtbase_%.bbappend

Add package to your image
• The easiest way is add following to your local.conf
IMAGE_INSTALL_append = " hello"
• Or create your own image, ex: coscup-image-minimal
coldnew@Sara ~/poky/meta-coscup $ mkdir -p recipes-core/image
coldnew@Sara ~/poky/meta-coscup $ vim recipes-core/image/coscup-image-minimal.bb
SUMMARY = "A console-only image for COSCUP2015"
LICENSE = "MIT"
# This image is based on core-image-minimal
include recipes-core/images/core-image-minimal.bb
IMAGE_INSTALL_append_qemux86 = " hello"
IMAGE_INSTALL_append_raspberrypi = ""
IMAGE_INSTALL += “
vim strace
”
# Add package-manager support
IMAGE_FEATURES += " package-management"
# Add ssh server support, or add ssh-server-dropbear here.
IMAGE_FEATURES += "ssh-server-openssh"

Create the SDK
• Use populate_sdk to generate image’s SDK
coldnew@Sara ~/poky/build $ bitbake core-image-minimal -c populate_sdk
• The sdks is locate at tmp/deploy/sdk dir
coldnew@Sara ~/poky/build $ ls tmp/deploy/sdk
poky-glibc-i686-core-image-minimal-i586-toolchain-1.8+snapshot.host.manifest
poky-glibc-i686-core-image-minimal-i586-toolchain-1.8+snapshot.sh
poky-glibc-i686-core-image-minimal-i586-toolchain-1.8+snapshot.target.manifest
• Install sdk by execute it
./poky-glibc-i686-core-image-minimal-i586-toolchain-1.8+snapshot.sh
Poky (Yocto Project Reference Distro) SDK installer version 1.8+snapshot
===========================================================
Enter target directory for SDK (default: /opt/poky/1.8+snapshot):
You are about to install the SDK to "/opt/poky/1.8+snapshot". Proceed[Y/n]?y
Extracting SDK…
Setting it up...done
SDK has been successfully set up and is ready to be used.
Each time you wish to use the SDK in a new shell session, you need to source
the environment setup script e.g.
$ . /opt/poky/1.8+snapshot/environment-setup-i586-poky-linux

• Remember to change the DISTRO variable in local.conf
Create your distro to make
local.conf more distributable
• It’s useful to distribute changes that have been made in local.conf
coldnew@Sara ~/poky/meta-coscup $ mkdir -p conf/distro
coldnew@Sara ~/poky/meta-coscup $ vim conf/distro/coscup.conf
# base on poky
require conf/distro/poky.conf
DISTRO = "coscup"
DISTRO_NAME = "Coscup (Example distro)"
DISTRO_VERSION = "1.0"
# Many config in local.conf can move here
DISTRO_FEATURES_append = " wayland"
# Use systemd as our runtime services
VIRTUAL-RUNTIME_init_manager ?= "systemd"
VIRTUAL-RUNTIME_initscripts ?= ""
DISTRO_FEATURES_append = " systemd"
DISTRO_FEATURES_BACKFILL_CONSIDERED = "sysvinit"
# Uncomment this for use uclibc instead of glibc
# TCLIBC = "uclibc"
DISTRO = "coscup"

Tips
&
Frequency Asked Questions

Package Management
• Enable package management by IMAGE_FEATURES
reference: http://www.yoctoproject.org/docs/1.8/mega-manual/mega-manual.html#runtime-package-management-build
IMAGE_FEATURES += " package-management"
# PACKAGE_CLASSES ?= "package_rpm package_deb package_ipk"
# We default to rpm:
PACKAGE_CLASSES ?= "package_rpm"
coldnew@Sara ~/coscup/build/tmp/deploy $ python -m SimpleHTTPServer 8000
PACKAGE_FEED_URIS = "http://10.0.2.15:8000"
• Make sure you build the deb, rpm or ipk package in local.conf
• Add feed url in your local.conf
• Start http-server in your deploy dir

Package Management (cont’d)
• apt-get (.deb)
reference: http://www.yoctoproject.org/docs/1.8/mega-manual/mega-manual.html#runtime-package-management-build
• smart (.rpm)
• opkg (.ipk)
root@qemux86:~# opkg update
root@qemux86:~# opkg install hexedit
• Refresh your package index
coldnew@Sara ~/coscup/build $ bitbake package-index
root@qemux86:~# smart update
root@qemux86:~# smart install hexedit
root@qemux86:~# apt-get update
root@qemux86:~# apt-get install hexedit

Use SDL instead of VNC when
runqemu
• If you don’t want to use vnc when execute runqemu
reference: [yocto] runqemu: vnc server running on ::1:5900
coldnew@Sara ~/coscup/build $ runqemu qemux86 core-image-sato
…
vnc server running on ::1:5900
#
# Qemu configuration
#
# By default qemu will build with a builtin VNC server where graphical output
# can be seen. The two lines below enable the SDL backend too. This assumes
# there is a libsdl library available on your build system.
PACKAGECONFIG_append_pn-qemu-native = " sdl"
PACKAGECONFIG_append_pn-nativesdk-qemu = " sdl"
ASSUME_PROVIDED += "libsdl-native"
• Add following to your local.conf
• Re-build qemu-native again
coldnew@Sara ~/coscup/build $ bitbake -c cleansstate qemu-native ;
bitbake qemu-native

Set default root password
• Add to your image’s bbappends
• ex: core-image-minimal.bbappend
inherit extrausers
ROOTPASSWORD = "123456789"
ROOTUSERNAME = "root"
EXTRA_USERS_PARAMS = "usermod -P ${ROOTPASSWORD} ${ROOTUSERNAME};"
inherit extrausers
ROOTPASSWORD = "123456789"
ROOTUSERNAME = "root"
pkg_postinst_${PN} () {
#!/bin/sh -e
# Note: Destination directory is available during boot
# process and unset at first boot
if [ -z $D ]; then
usermod -p ${ROOTPASSWORD} ${ROOTUSERNAME};
fi
}
or
reference: https://wiki.yoctoproject.org/wiki/FAQ:How_do_I_set_or_change_the_root_password

FATAL: kernel too old
• Building glibc need to specify kernel version
• conﬁgure --enable-kernel=2.6.32 when building glibc
• Add to your local.conf
• Since glibc 2.20 the minimal required kernel is 2.6.32
• You can’t use dizzy (1.7) or above if your kernel version is less
than 2.6.32
• For more info, please see here and here
OLDEST_KERNEL = “2.6.32"
reference: [yocto] Glibc kernel version depends

PR-Service
• Add to your local.conf to enable PR-Service locally
# Enable prservice to auto incremental PR value
# see: https://wiki.yoctoproject.org/wiki/PR_Service
PRSERV_HOST = "localhost:0"
• It’s annoying to upgrade PR variable when change recipes
• How to share current package PR version across different build host ?
• Use PR-Service to solve these issue (not enable by default)
• Start PR server (server ip: 192.168.1.123, port: 9090)
# Enable prservice to auto incremental PR value
# see: https://wiki.yoctoproject.org/wiki/PR_Service
PRSERV_HOST = “192.168.1.123:9090”
coldnew@Sara ~/poky/build $ bitbake-prserv —host <server ip> —port <port> --start
• In local.conf

Misc
• Add to your local.conf to set default timezone
DEFAULT_TIMEZONE="Asia/Taipei"
• Add to your local.conf to save disk spaces
# Uncomment this to delete work files as the build progresses rather than
# keeping them around, which saves a lot of disk space. However, if any
# problems arise it can be useful to have the work files to examine, which
# is why it is off by default.
INHERIT += "rm_work"
PREFERRED_VERSION_hello = “0.1”
PREFERRED_VERSION_lighttpd = "1.4.35"
• Lock package version

Buildhistory
• Add following to your local.conf
INHERIT += "buildhistory"
BUILDHISTORY_COMMIT = "1"
• You can use buildhistory-diff see changes in different build
coldnew@Sara ~/poky/build $ buildhistory-diff
• You can use buildhistory-diff see changes in different build
coldnew@Sara ~/poky/build/buildhistory $ tree -L 2 .
.
!"" images
$ #"" qemux86
!"" metadata-revs
#"" packages
!"" all-poky-linux
!"" i586-poky-linux
!"" qemux86-poky-linux
#"" x86_64-linux

Buildhistory (cont’d)
coldnew@Sara ~/poky/build/buildhistory $ ls
build-id.txt files-in-image.txt
depends.dot image-files
depends-nokernel.dot image-info.txt
depends-nokernel-nolibc.dot installed-package-names.txt
depends-nokernel-nolibc-noupdate.dot installed-package-sizes.txt
depends-nokernel-nolibc-noupdate-nomodules.dot installed-packages.txt
digraph depends {
node [shapeplaintext
"udev" -> "libblkid1";
"udev" -> "libc6";
"udev" -> "libkmod2";
"udev" -> "udev-cache" [styledotted;
"udev" -> "update-rcd" [styledotted;
"udev-cache" -> "update-rcd" [styledotted;
"v86d" -> "kernel-module-uvesafb" [styledotted;
"v86d" -> "libc6";
"v86d" -> "update-rcd" [styledotted;
}
• See dependencies in depends.dot

lrwxrwxrwx root root 19 ./bin/usleep -> /bin/busybox.nosuid
lrwxrwxrwx root root 19 ./bin/vi -> /bin/busybox.nosuid
lrwxrwxrwx root root 19 ./bin/watch -> /bin/busybox.nosuid
lrwxrwxrwx root root 19 ./bin/zcat -> /bin/busybox.nosuid
drwxr-xr-x root root 4096 ./boot
drwxr-xr-x root root 4096 ./dev
drwxr-xr-x root root 4096 ./etc
-rw-r--r-- root root 2276 ./etc/busybox.links.nosuid
-rw-r--r-- root root 91 ./etc/busybox.links.suid
drwxr-xr-x root root 4096 ./etc/default
• See all ﬁles in ﬁles-in-image.txt

3104 KiB libc6
612 KiB udev
537 KiB busybox
283 KiB libblkid1
135 KiB sysvinit
126 KiB v86d
90 KiB libkmod2
89 KiB libz1
32 KiB kernel-module-uvesafb
25 KiB initscripts
23 KiB netbase
• See all package size in installed-package-sizes.txt

Mailing Lists
• Yocto Project Discussions (yocto)
• Discussion with Yocto Project developers - start here with general
questions.
• Yocto Project Announcements (yocto-announce)
• Announcements of project developments and milestones. Low trafﬁc.
• Builds (yocto-builds)
• Automated feed for autobuilder results.
• OpenEmbedded Core Developers
• Developer discussions about the openembedded-core layer. *
reference: https://www.yoctoproject.org/tools-resources/community/mailing-lists

Where to Send Patches
reference: see README in poky
Where to Send Patches
=====================
As Poky is an integration repository (built using a tool called combo-layer),
patches against the various components should be sent to their respective
upstreams:
bitbake:
Git repository: http://git.openembedded.org/bitbake/
Mailing list: bitbake-devel@lists.openembedded.org
documentation:
Git repository: http://git.yoctoproject.org/cgit/cgit.cgi/yocto-docs/
Mailing list: yocto@yoctoproject.org
meta-yocto(-bsp):
Git repository: http://git.yoctoproject.org/cgit/cgit.cgi/meta-yocto(-bsp)
Mailing list: poky@yoctoproject.org
Everything else should be sent to the OpenEmbedded Core mailing list. If in
doubt, check the oe-core git repository for the content you intend to modify.
Before sending, be sure the patches apply cleanly to the current oe-core git
repository.
Git repository: http://git.openembedded.org/openembedded-core/
Mailing list: openembedded-core@lists.openembedded.org
Note: The scripts directory should be treated with extra care as it is a mix of
oe-core and poky-specific files.

How to Send Patches
reference: see README in meta-qt5
Send pull requests to openembedded-devel@lists.openembedded.org with '[meta-qt5]' in the
subject'
When sending single patches, please using something like:
'git send-email -M -1 --to openembedded-devel@lists.openembedded.org —subject-prefix=meta-
qt5][PATCH'
coldnew@Sara ~/poky/meta-qt5 $ git send-email -M -1 --to openembedded-
devel@lists.openembedded.org —subject-prefix=meta-qt5][PATCH
• Take meta-qt5 as example
• After commit to local repo, use git-send-email to send patch

Want to Learn More ?
• Yocto project and open embedded training
• Poky meets Debian: Understanding How to
Make an Embedded Linux by Using an Existing
Distribution's Source Code

Example: hello_0.1.bb
LICENSE = "MIT"
PR = "r0"
SRC_URI = "file://helloworld.c"
S = "${WORKDIR}"
do_compile() {
${CC} helloworld.c -o helloworld
}
do_install() {
install -m 0755 helloworld ${D}${bindir}
}
BBCLASSEXTEND = "native nativesdk"
coldnew@Sara ~/coscup/build $ bitbake hello
coldnew@Sara ~/coscup/build $ bitbake hello-native
coldnew@Sara ~/coscup/build $ bitbake nativesdk-hello

Example: hexedit
SUMMARY = "view and edit files in hexadecimal or in ASCII"
HOMEPAGE = "http://rigaux.org/hexedit.html"
SECTION = "console/utils"
LICENSE = "GPLv2+"
DEPENDS = "ncurses"
LIC_FILES_CHKSUM = "file://COPYING;md5=0636e73ff0215e8d672dc4c32c317bb3"
SRC_URI = "http://rigaux.org/${BP}.src.tgz
file://0001-don-t-strip-when-installing.patch "
SRC_URI[md5sum] = "a5af1378d028512a9cad27a5ba3e15f9"
SRC_URI[sha256sum] = "6a126da30a77f5c0b08038aa7a881d910e3b65d13767fb54c58c983963b88dd7"
inherit autotools-brokensep
S = "${WORKDIR}/${BPN}"
reference: autotools-brokensep: Mark recipes with broken separate build dir support
meta-oe/recipes-extended/hexedit/hexedit_1.2.13.bb
BP = hexedit-1.2.13
BPN = 1.2.13
autotools-brokensep is for those which use autotools but don’t support a separate
build directory ( ${S} != ${B} )

• Add to your local.conf
Customizing the Image
• Add EXTRA_IMAGE_FEATURES
=
“<feature>”
Option description
dbg-pkgs -dbg packages for all installed packages
dev-pkgs -dev packages for all installed packages
tools-sdk Development tools such as gcc, make
tools-debug Debugging tools such as gdb and strace
tools-testapps Testing tools such as ts_print, aplay
debug-tweaks Makes an image suitable for development, ex: no password
EXTRA_IMAGE_FEATURES = " debug-tweaks dev-pkgs"

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