Introduction to OpenBricks: an Embedded Linux Framework

Introduction to OpenBricks: an Embedded Linux Framework

Benjamin Zores

6th February 2011
FOSDEM, Brussels

What is OpenBricks ?

Enterprise-grade embedded
Linux framework and build system.

For easy and custom Linux distribution bring-up.

Runs on a wide variety of hardware.

For rapid prototyping or full-blown product development.

• “Hum, seems like I’ve already heard about that ...
So how is it different from … ?”

B. Zores – FOSDEM 2011

State of the Art

2011 Embedded Linux build systems:

• OpenEmbedded (Angström, Poky, Yocto, ...)

• Buildroot

• OpenWRT

• T2 SDE

• Linux Target Image Builder (LTIB)

• “Professional”: Windriver, Montavista, Mentor Graphics …

• And now OpenBricks ??

• More details in a further talk, but in the mean time:
http://tinyurl.com/EmbeddedLinuxBuildSystems


So why yet another build system in 2011 ?

Because Google’s Android is not the perfect embedded OS.

History:
• OpenBricks “brand” in itself was founded in Oct. 2010.
• But came as an extension to the GeeXboX project - © 2002.
• Inherited toolchain and philosophy,
but designed to be more versatile.
• Now used as custom build framework for GeeXboX OS.

Each build system has pros and cons,
but projects all have very different philosophies.
• So it’s not exactly new …


The 5 minutes Overview

Embedded Linux build framework
for individuals and/or enterprises for either
easy prototyping or full-blown products development.

Replaces traditional BSPs with a fine-grained
package tuning ability (through kconfig interface).

Support for x86, ARM, PowerPC and MIPS architectures
with reference boards optimizations.

Brings up low-level system and features
major applicative frameworks (Qt, EFL, GTK, SDL)
for developers to only focus on end-user applications.

Multimedia-oriented but with general purpose:
• Currently sustains the GeeXboX STB OS project.
• But allow you to build your unique one too …


Supported Architectures

x86 (32/64 bits):
from generic builds to custom ATOM/ION optimized ones.

PowerPC (32/64 bits)

MIPS (32 bits)

ARM:

• ARM9 (e.g. Marvell Kirkwood …)
• ARM11 (e.g. Broadcom BCM11107 Persona family …)
• Cortex A8 / A9 (e.g. TI OMAP3, TI OMAP4, nVidia Tegra250 …)

With known reference boards optimizations:
Beagleboard, IGEPv2, Touchbook, Pandaboard …

Much more to be expected:
Freescale i.MX, Qualcomm SnapDragon,
Marvell Armada, Intel CE4xxx …


Applicative Features

Supported Languages:

• Shell, C, C++, Python, Perl, Lua, Vala

Supported Frameworks:

• Nokia Qt 4.7.1 with support for:

• Webkit
• QtMobility
• QtDeclarative / QML

• Enlightenment EFL 1.0

• GTK+ 2.22

• SDL Simple DirectMedia Layer 1.2


Multimedia Features - Graphics

Native framebuffer interface.
Accelerated DirectFB engine.
Accelerated X11 Infrastructure.

Support for Khronos group standards:
• EGL Native Platform Graphics Interface

• Desktop OpenGL 3.0

• Embedded OpenGL|ES 2.1

• Embedded OpenVG 1.0

• Provided either by Mesa or by manufacturer’s binary blobs.


Multimedia Features - Audio/Video

Audio Frameworks:
• ALSA, PulseAudio

Software Video Frameworks:
• SMP-optimized FFmpeg decoders.

Hardware Video Frameworks:
• Khronos OpenMAX (OMAP3, OMAP4, Tegra2).
• nVidia VDPAU (x86 with nVidia GeForce GPU).
• Freedesktop VA-API (x86 with Intel or ATI GPUs).
• Broadcom CrystalHD (BCM 70012/70015 chips).
• Other native SoC acceleration (OMAP3, OMAP4).


Multimedia Features - Applications

Frameworks and Players:

• MPlayer, Xine, GStreamer, VLC

• libplayer Audio/Video abstraction framework

Media Center frontends:

• XBMC

• Video Disk Recorder (VDR)

• Enna

• HTS Showtime

• Nokia QtMediaHub

• MythTV


Build System Overview

Fully POSIX shell scripts based:

• Easy understanding, hacking and maintenance ...
• … at least much more than obfuscated Makefiles or Python stuff ;-)

Does not require any externals tools or environment.
• Required host build tools and packages are built along the way.

• Cross-Compilation Safety and Robustness
• Triggers GCC internal errors on -I/usr/include and -L/usr/lib

Fully customizable:

• Supports customized distribution flavours
pre-generated configurations.
• Complete standalone package/feature selection
through Kconfig interface.
• Per-package fine-tuning through use flags (similar to Gentoo).

Features per-package metadata rules for abstracted in/out.
With more than 550 supported packages.


Toolchain Overview

Support for multiple GCC-based cross-compilers:

• OpenBricks multi-architectures native one.

• Linaro for ARM.

• CodeSourcery for ARM.

• Support for multiple C libraries:

• GNU libc (glibc)

• Embedded GLIBC (eGlibc). This is default one !

• uClibc

• klibc (for early ramdisk bits).

Do your own mix !


Configuration Overview (1/2)

Up to 3-levels of hardware configuration tuning:

• Architecture (e.g. ARM, x86 …)

• Platform (e.g generic, OMAP3, OMAP4 …)

• Machine (e.g. generic, Beagleboard, IGEPv2 …)

• The deeper, the more optimized (footprint, selected packages …),
but the less portable …

-> it’s up to you to choose depending on your needs !

Automatic package inter-dependencies
selection and build process.

Support for per arch/platform/machine package overlay.


Configuration Overview (2/2)

Features fine-tuning through “use flags” (similar to Gentoo):

• Conditionally build specific features.

• Enable flags per-package or system-wide.

• You can also have package-specific flags.

• Infinite number of them …

Pre-determined packages subset, a.k.a. build flavours:

• Minimalist base bootable system.

• GeeXboX MediaCenter-oriented distribution.

• Add your own distro here !


Key Build Framework Features

Bleeding-edge packages: latest stable package version policy.

Support for arch/platform/machine
specific package overlay (sources, patches …).

Modern user-space: systemd, udev, D-Bus, connman …

Stuff gets packaged into low-resources OPKG packages.

Multiple OPK build residue: runtime, devel, debug.

Multiple target system delivery forms:
• Flashable disk images: JFFS2, UBIFS, EXT 2/3/4.
• x86 LiveCD (ISO) and network (PXE) bootable images.
• Flat root filesystem
• Virtual machines images: QEMU, VMware


Package Description Template

Files Structure:

• build: cross-build rules

• install: installation rules for target (optional)

• installdev: installation rules for host toolchain (optional)

• meta: metadata, use flags and package description.

• unit (optional)
• package.service: systemd service.

• patches (optional)
• 01_fix.diff
• 02_feature.diff
• series (optional)


“Simple” package example: syslink (1/4)

●
Metadata description:

PKG_NAME=syslink
PKG_VERSION=0.24.9.2
PKG_URL="$DISTRO_SRCS/tisyslink-${PKG_VERSION}.tar.bz2"
PKG_REV=1
PKG_DEPENDS="$TARGET_LIBC tiler"
PKG_BUILD_DEPENDS="toolchain"
PKG_PRIORITY=optional
PKG_SECTION=libs
PKG_SHORTDESC="TI OMAP4 SysLink DSP interface"
PKG_LONGDESC="SysLink is the next generation IPC driver
developed for OMAP4 and beyond. SysLink is an evolution of
both the previous-generation IPC drivers - DSPBridge and
DSPLink."



Build Rules:

#!/bin/sh
. config/options

cd $BUILD/$1*
do_configure
--disable-debug

make
make_install



Toolchain installation files rules (dev opk file):

do_installdev usr/include
do_installdev usr/lib

Runtime target installation files rules (runtime + dbg opk file):

do_install usr/bin/syslink_daemon.out
do_install usr/lib/libipc.so*
do_install usr/lib/libipcutils.so*
do_install usr/lib/libomap4430proc.so*
do_install usr/lib/libprocmgr.so*
do_install usr/lib/librcm.so*
do_install usr/lib/libsyslinknotify.so*
do_install usr/lib/libsysmgr.so*



SystemD Service:

[Unit]
Description=Ducati Syslink daemon
ConditionPathExists=/etc/syslink.conf
After=syslog.target

[Service]
EnvironmentFile=/etc/syslink.conf
Type=forking
ExecStart=/usr/bin/syslink_daemon.out $SYSM3_IMAGE $APPM3_IMAGE
Restart=always

[Install]
WantedBy=multi-user.target


“Average” package example: libplayer (1/2)

Metadata description:

PKG_NAME=libplayer
PKG_VERSION=2.0.1
PKG_URL="http://libplayer.geexbox.org/releases/libplayer-
$PKG_VERSION.tar.bz2"
PKG_REV=1
PKG_BUILD_DEPENDS="toolchain"
PKG_RUN_DEPENDS="$TARGET_LIBC"

PKG_USE="gstreamer xorg vdpau"

# gstreamer
PKG_USE_DESC_gstreamer="Enable GStreamer backend"
PKG_USE_HELP_gstreamer="Enables the GStreamer backend."
PKG_DEPENDS_gstreamer="gstreamer gst-plugins-base"

# xorg
PKG_DEPENDS_xorg="libX11"
PKG_DEPENDS_vdpau="libvdpau"


“Average” package example: libplayer (2/2)

Build Rules:

#!/bin/sh
. config/options

XORG_CONFIG="--disable-x11"
pkg_uses $1 xorg &&
XORG_CONFIG="--enable-x11 --enable-xlib-hack"

GST_CONFIG="--disable-gstreamer"
pkg_uses $1 gstreamer && GST_CONFIG="--enable-gstreamer"

cd $BUILD/$1*
do_configure
$GST_CONFIG
$XORG_CONFIG
--cross-compile
--disable-doc
make && make_install


How you can one help (or get helped) ?

Get some help or information:
• Website provides a complete documentation on build system internals.
• On our mailing list: devel@openbricks.org

Join the development team:
• Add new packages, hence features.
• Add support for new/more hardware (yours ?).
• Increase flavours support by adding your custom distribution subset.

Sponsor us with a couple of reference boards.
• Only way for the team to really support your architecture …
• We’re still interested in Intel / Freescale / Qualcomm / Marvell boards.

Donations
• The usual way: helps us buy new toys to be supported ...


Thanks ...

http://www.openbricks.org/

THANKS !!


Introduction to OpenBricks: an Embedded Linux Framework

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