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Documentation/Maemo 5 Developer Guide/Architecture/Core Domain

Revision as of 14:34, 2 September 2010

Nolo bootloader

Name

NoLo (Nokia Loader)

Purpose

The bootloader does basic configuration of the HW, loads the kernel into memory, and passes control to the kernel. In addition to this basic task the NoLo boot loader has many features to support R&D. (The capability to flash the device is currently implemented in NoLo but it will become an R&D feature once flashing is moved to user space.)

Responsibilities

• Load kernel into memory
• Initialize HW so that kernel is able to boot
• Pass ATAGs to the kernel and transfer execution to the kernel
• Production line flashing functionality
• Creates partitions

Package / License

nolo / Nokia

Linux Kernel

Purpose

The function of the kernel code is to provide all the basic services and hardware interfaces of the Linux operating system for the underlying programs. The kernel also passes the control to the chosen user space program (usually /sbin/init) after initializing its own structures and drivers. When the kernel starts up, it checks a lot of the available subsystems and initializes everything according to the kernel configuration chosen at compile time. Some subsystems will be left uninitialized by the boot loader, for example, the display subsystem.

Responsibilities

The operating system kernel

Notes

Maemo specific functionality is in OMAP3 & Rover HW specific code. OMAP3 support is developed, generally speaking, in the linux-omap tree, from which code is pulled into Maemo kernel.

Package / License

kernel / GPL2

Public interfaces provided

Linux kernel API: Linux system calls accessed through the C library

Kernel core services

Purpose

The Linux core services comprise generic, hardware independent code.

Responsibilities

• memory management
• process management
• device management
• inter-process communication…

Notes

Used as is.

Package / License

kernel / GPL2

ARM architecture support

Purpose

The ARM architecture subsystem in the kernel provides mainly ARM specific implementations of necessary core mechanisms.

Responsibilities

ARM specific implementations of kernel mechanisms.

Notes

Used as is.

Package / License

kernel / GPL2

Kernel framework

Purpose

The low level HW drivers provide the concrete implementation that is bound to the virtual services in the Linux kernel to provide the complete functionality.

Responsibilities

• ALSA & Video for Linux 2 (V4L2) APIs,Networking stack, BlueZ (Bluetooth), mac80211 (WLAN), USB core
• Virtual File System, file systems, block devices, MTD
• Frame buffer, serial port, input layer (keyboard, touch screen)

Package / License

kernel / GPL2

Public interfaces provided

• ALSA: Advanced Linux Sound Architecture, de facto Linux sound API.
• V4L2: Video for Linux 2, de facto video capture API + Maemo specific ioctls
• Camera ioctls: Extensions to V4L2 interface used by the camera daemon.
• File systems: FAT16/32, EXT3 and UBIFS file systems are currently supported on the platform.
• Frame buffer: The raw frame buffer interface is used in early stages of the boot.
• Input layer: The input layer events are routed via X to applications.
• Serial port: Available for R&D use.

OMAP3 support

Purpose

OMAP specific code implements the device drivers and bus support for the specific hardware included in the OMAP3430 chip. The supported OMAP3 subsystems are described in the following subsections.

Responsibilities

• DMA: OMAP3 has a 32 channel general purpose DMA controller, display DMA, HS USB DMA, and IVA 2.2 DMA (not supported).
• Interrupt handling:OMAP3 has an interrupt controller (MPU INTC) with 96 synchronous interrupt lines.
• OMAP3 specific power management functionality: The power management functionality is built on top of idle, sleep, suspend, resume, and dynamic voltage & frequency scaling functionalities [SystemSW].
• DSP Bridge, ioMMU, OMAP watchdog, GPIOs, timers, Muxing framework
• Gpmc (OneNAND driver), hsmmc (MMC/SD)
• Bus drivers: spi, i2c, McBSP, uart, SSI

Package / License

kernel / GPL2

DSP Bridge

Purpose

OMAP's integrated DSP allows offloading tasks to the DSP from the ARM processor. This is exposed with the DSP bridge component.

Responsibilities

Interface to the OMAP3’s DSP which is used for codec acceleration.

Package / License

kernel / GPL2

OMAP3 bus drivers

Responsibilities

Drivers for the following buses: SPI, SSI, McBSP, GPIOs, HS MMC/SD, UART, I2C/I2S, RFBI, CBUS, Flash BUS, (STI/XTI debugging interfaces)

Package / License

kernel / GPL2

OMAP3 specific HW drivers

Responsibilities

Drivers for following HW components:SGX, OMAP framebuffer & LCD & TV-out, Camera & ISP, HS USB Host & HS USB OTG, SDRAM memory controller, GPMC NAND/NOR flash&SRAM controller, and PRCM

Package / License

kernel / GPL2

Specific hardware drivers

Responsibilities

The following components external to OMAP are supported: USB transceiver, USB charging, FM RX/TX, WLAN, OneNAND flash, touch screen, audio, stereo IHF, earphone, digital mics, LEDs, HW keys, ALS, Accelerometer, Vibrator, Proximity sensor, Miscellaneous Sensors, LCD backlight, Bluetooth, WLAN, CMT, Ethernet (R&D use).

Package / License

kernel / GPL2

X Window System

Purpose

Graphical User Interface framework

Responsibilities

• XServer – GUI framework & resource management
• Xv – Video playback interface
• XRandR – Support for rotation & output configuration
• XRender, XComposite – Support for composited UI
• XInput – Routing of input events to applications

Package/ License

Several/ MIT

Public interfaces provided

• X protocol: Interface to the X window system
• DRI2: Direct Rendering Infrastructure 2, OpenGL ES 2.0

OpenGL ES 2.0

Purpose

Accelerated 3D rendering

Responsibilities

• Accelerated 3D rendering
• Acceleration of XRender

Notes

The user space GLES components are licensed from Imagination.

Package/ License

opengles2-sgx-img-common, libgles2(-sgx-img/-sgx-img) / Nokia

Public interfaces provided

EGL: Khronos API for OpenGL ES application for interacting with the native graphics framework.

C library

Purpose

Posix C library functionality

Responsibilities

• System call interfaces
• Posix functionalities

Package/ License

glibc / LGPL2

Essential tools

Purpose

The essential tools provide tools needed in system scripts. The role is similar to the Debian essentials (tools that are always installed in a Debian system).

Responsibilities

system tools like: shell, grep, find, dpkg, …

Notes

Many tools have many limitations compared to the Debian versions. Not all Debian essentials are supported.

Package/ License

busybox / GPL2

Public interfaces provided

• Posix shell
• Subset of Debian essentials

Sysinfod

Purpose

Provide interface for accessing device information

Responsibilities

Provide a D-Bus interface to device specific information (HW id, WLAN MAC, …)

Package / License

sysinfod / Nokia

Public interface provided

Sysinfod D-Bus interface

Softupd

Purpose

Program for flashing the eMMC contents

Responsibilities

• Unpacks a FIASCO image fed to it
• Copies the unpacked contents to eMMC

Package / License

softupd / Nokia

Fiasco-flasher

Purpose

Tool for updating the kernel flashed to the device

Responsibilities

• Flash kernel image into the kernel partition
• Reboot the device

Package / License

fiasco-flasher / Nokia

Public interface provided

Fiasco-flasher: The tool can be used to flash a new kernel image into the kernel partition.