The document provides an overview of the Maemo 5 architecture, including the hardware architecture of the Nokia N900, the software architecture of Maemo 5, and the developer tools architecture using Scratchbox. It describes the modular, open source-based design of the Maemo 5 software stack and its subsystems like the desktop, toolkits, multimedia, and core system components. It also outlines the deployment APIs and typical application development using the Maemo SDK and Scratchbox cross-compilation tools.

1. Maemo 5 Architecture
Overview
Tapio Tolvanen
Chief Architect, Maemo US
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2. Contents
• Introduction
• HW Architecture (Nokia N900)
• SW Architecture (Maemo 5)
• Developer tools architecture
• Q&A
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3. Maemo 5 Architecture
Introduction
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4. Product Multimedia Computer
Internet Optimized
evolution
Nokia N900
Nokia N810
WiMAX Edition
Nokia N810
Nokia N800
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Nokia 770
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5. Software developed with the
community
14.000 members
700 hosted
projects
200 applications
Maemo
Nokia is a key
contributor to
Community projects such as
GNOME/GTK+.
Open source
projects
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6. Maemo 5 Architecture
HW Architecture
Top Level view
Runtime view
“Developer” view
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7. Top level view
Runtime view Peripherals
Keyboard, vibra, actuators…
WLAN
N900
(802.11g) …
OMAP 3430
Bluetooth
Proximity
(v2.1) Cortex A8
(ARM)
Modem SPI
I2C ALS
(HSPA) SSI PowerVR
DSP
SGX
USB Accelero-
(HS 2.0) SDRAM ctrl, DMA, …
meter
McBSP, UART
LCD Camera Camera
Touch MMC/SD
(800x480) (5 Mpx) (VGA)
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8. Runtime view - boot
rootfs
[initrd]
kernel
code
boot
loader
boot
ROM
code
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9. Runtime view – Storage
FLASH partitions Size Comments
Boot loaders… ~ 600 kB
Kernel 2048 kB
Initfs 2048 kB Not used
Rootfs 257280 kB UBIFS, “/”
eMMC partitions Size (32GB) Comments
/home/user/MyDocs ~ 28 GB FAT32
/home 2 GB ext3, /home/opt
/swap 768 MB swap
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10. Developer view – Interfaces provided
Component Low level interface Comments
Accelerometer sysfs HAL, MCE
Ambient light sensor sysfs HAL
Bluetooth BTH, ALSA Bluez
Camera(s) V4L2 gstcamerabin
DSP DSP Bridge/OpenMAX gst elements
FM TX ALSA
Graphics accelerator driver, EGL OpenGLES2.0, clutter
LCD framebuffer toolkits
LEDs sysfs MCE, HAL
MMC/SD Block device ext3, vfat
Peripherals sysfs, input layer MCE, HAL
TV-out Xrandr
USB driver LINUX HS USB OTG
WLAN
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11. Maemo 5 Architecture
SW Architecture
Target
Top level view, logical view, process view
Subsystem examples
Deployment view
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12. Solid target SW architecture on Linux – first in
taking Linux desktop paradigm to mobile devices & now in its
5th generation
Objective: Solid, high performance software
architecture for Linux-based multimedia computer
– modular, secure, open, and expandable.
Design characteristics: Allow collaborative
development of operating system components in
open source projects and differentiation by Nokia in
user experiences.
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13. Top Level Architecture
<<layer>> Independent applications
People, Places, Media, Internet Maemo services
Maemo platform interface
Middleware interface
<<layer>> Middleware
AF, Content, Context, System, Multimedia, Communications, Runtimes
Base interface
<<layer>> base
Essentials; Kernel; Multimedia, Graphics, Communications & System
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adaptation
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14. Rockstars in subsystem view
Desktop Hildon desktop Clutter
Toolkits Qt GTK+, GDK SDL
Data mgmt SQLite Debian pkg mgmt Tracker
Communic. Telepathy GUPnP BlueZ
Multimedia PulseAudio GStreamer MAFW
linuxwireless.org OpenGL ES
V4L2 OHM upstart
Core
BusyBox Gconf D-Bus
System
Xorg HAL GLib
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15. Process view
Run as System processes UI server
processes
user dsme hildon-desktop
nobody bme hildon-input-method
haldaemon mce sapwood server
messagebus dbus-daemon hildon-home
root maemo-launcher
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16. Deployment view – APIs System SW APIs
* libhal
RTCOM APIs * libhal-storage
Toolkit APIs Multimedia APIs
* telepathy-glib * libalarm
* Gio * gstreamer
* farsight2-libs * mce-dev
* Glib * gstreamer-libs
* libprofile
* Gobject * gstreamer-plugins-0.10 * farsight2-plugins
* GTK+ * pulseaudio * telepathy-farsight
* ATK * gupnp * libnice
* GDK * gupnp-av * libaccounts Connectivity APIs
* GDK-pixbuf * libcanberra * libosso-abook * libconic
* dbus * libmafw * libebook * libgwobex
* dbus-glib * libspeex * libedataserver * bluez
* gconf * mafw-shared * osso-wlan
* pango * libsoup * icd2
* cairo Hildon APIs
* clutter * libhildon
Application Interface APIs * libhildondesktop
* calendar-backend * libhildonfm
* libcityinfo * libosso
* libtime * libnotify
* liblocation * libtracker-common
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17. Deployment view – Typical application
Application
A typical UI application
Hildon
GTK+
Gnome VFS GStreamer libosso
GConf2
Pango ATK
Cairo D-Bus
GObject GLib
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18. Maemo 5 Architecture
Developer tools architecture
Scratchbox
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19. Maemo SDK basics
Development environment
Uses Scratchbox
masquerades host system and tools to look like target
fixes tools rather than packages for cross compilation
similar development process to normal desktop
Why Scratchbox?
a lot of reuse of existing components in OSS projects
these components are not designed to be cross compiled
speed of development
Simple to use
apt-get source <any standard Maemo distribution package>
dpkg-buildpackage
Flexible execution
X86, ARMEL, qemu
Supported programming languages
C, C++ and Python (C officially)
The actual Maemo SDK is
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Set of preconfigured Scratchbox targets and root file systems
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20. Scratchbox architecture
Scratchbox sandbox
OS platform:
“scratchbox” software for target
devkits toolchains rootstrap
CPU transparencies
host tools
PC Host
sbrsh/nfs
Target device
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21. That’s all folks!
Thank you!
Tapio Tolvanen
Chief Architect, Maemo US
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