Architecture

Mer Architecture

Mer architecturally derives from the MeeGo 1.3 architecture. The big changes in MeeGo 1.3 compared to MeeGo 1.2 was systemd inclusion, which simplified much of the startup process and services handling. Mer architecture was based around the need for a minimal Core that could be the basis of many different kinds of products.

As such, in the transformation of MeeGo to Mer, only packages and dependencies that served a practical purpose for the criteria of booting up to a Xorg+Qt qmlviewer with connectivity and ability to expand upon that was left in. This meant a much smaller set of packages were put together and hence your favourite package will probably not be part of Mer.

Another difference from MeeGo is that in Mer, we do not contain hardware adaptations and reference user interfaces. Architecturally, hardware adaptations are plugging into abstract 'adaptation interfaces' of the Mer Core, which means that when you couple the Mer Core with a hardware adaptation, you get a booting system. If you add a user interface of your selection on top, you have a working device with UI.

The reasoning for no hardware adaptations or reference user interfaces stems from experiences within MeeGo, where hardware adaptations were often completely out of sync with the release schedule of the Core and the reference user interfaces reflected badly on the MeeGo Core's actual abilities, along with release pressures giving a lesser quality Core, UIs and hardware adaptations.

Essentials

Central Libraries

Essentials/Central Libraries in context

Mer utilizes EGLIBC 2.15 as it's central C Library, with Linaro GCC 4.6 as toolchain.

GNU utilities

Essentials/GNU utilities in context

Mer standard build-time and run-time configuration utilizes GNU utilities such as bash, coreutils, sed, ncurses, gzip, gawk, findutils, readline, etc.

For the utilities making it into run-time images, we try to avoid GPLv3 versions. In the future it will be possible to utilize busybox as a replacement for run-time to solve this issue better.

Base Essentials

Essentials/Base Essentials in context

Linux utilities

Essentials/Linux utilities in context

D-Bus

Essentials/D-Bus in context

For inter-process communication, Mer utilizes D-Bus as messaging bus.

Software Management

Package Manager

Software Management/Package Manager in context

Mer utilizes the RPM package manager as backend for the Zypper package manager, which handles repositories and fetching RPMs and looking for available updates, etc.

Communications

ConnMan

Mer utilizes the ConnMan connection manager for managing internet connections.

Cellular Framework

Mer utilizes the oFono telephony stack

Bluetooth

Communications/Bluetooth in context

Mer utilizes the BlueZ Bluetooth protocol stack

Proxy Management

Mer provides the libproxy API, with pacrunner as backend

Graphics

OpenGL ES

3D-accelerated Software built against Mer should be utilizing the OpenGL ES 2.0 and EGL native platform interface APIs. Mer Core provides the open source Mesa 3D Graphics Library containing OpenGL ES 2.0 and EGL libraries to link and build against, which can at image build time be replaced with device-specific OpenGL ES 2.0/EGL implementations.

In Mer Core, Mesa is built to be utilizing LLVMpipe for fast software rendering with no hardware specific drivers enabled.

Fonts

Mer provides a minimum of freely distributable fonts, the CJKUni fonts, Droid fonts, Liberation fonts.

System

System Control

Mer utilizes the systemd system and service manager for Linux. This approach is much different from typical SysV init scripts, but is also more suitable for mobile systems due to on-demand starting of daemons.

Multimedia

GStreamer

Mer utilizes the GStreamer multimedia framework for playback, encoding, filtering of media, etc.

PulseAudio

Mer utilizes the PulseAudio networked sound server.

Codecs

Mer provides codecs such as FLAC, Ogg Vorbis/Theora/Speex, with ability to add more through the GStreamer Framework.