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Embedded Linux Systems

Embedded Linux Systems. Jesper Holt Nielsen. Overview. Short about Linux Linux Distributions Embedded Linux Systems Basics Open Embedded Framework (OE) Basics Bitbake Ängstrom dist. Linux. Kernel Manage input/output requests from software Distro on top of the Kernel

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Embedded Linux Systems

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  1. Embedded Linux Systems Jesper Holt Nielsen

  2. Overview • Short about Linux • Linux Distributions • Embedded Linux Systems • Basics • Open Embedded Framework (OE) • Basics • Bitbake • Ängstrom dist.

  3. Linux • Kernel • Manage input/output requests from software • Distro on top of the Kernel • Different user layers and privileges • User space • Kernel space • Root File System • Same partition as the root dir • Top-most directory • GPIO

  4. Device Drivers • Hardware specific drivers • Hardware dependant • Loaded with the kernel (build into) • Communicate through the computer bus • Translator between hardware and applications (or OS) • Interrupt handling to the HW

  5. Kernel Modules • Extend running kernel • Add support for new hardware • Hardware specific drivers (usually) • Not build into the Kernel • Loaded and tested on the fly • With lsmod, insmod, rmmod (modprobe) • .ko extension (Kernel Object)

  6. Linux GPIO • Folder structure of devices available • Easy GPIO access from userspace • /sys/class/gpio • Control interfaces used to get userspace control over GPIOs • With export and unexport • Ask kernel to export control of a GPIO to userspace(given by a number)

  7. Linux Distribution • Operating system on top of a kernel • Can be specific to hardware devices • Collection of software (free- / open-source) • Managed by repositories • Range from fully featured distros to minimal distros (Embedded systems) • 600+ Linux distrobutions

  8. Embedded Linux SystemsOverview • System with dedicated function • Dedicated to handle a specific task • Optimized in size and cost • Increase reliability and performance • Part of a larger system • Mechanical or electronical • Microcontrollers • Widespread use, cosumer products to industrial use

  9. Open Embedded Framework (OE) • Set of metadata used to cross-compile • Packages, software • Used to build and maintain • Various Embedded Linux Distributions • For example Ängstrom • Use the Bitbake build tool • Collects and manages package recipies • Controls how to build things, plus dependencies

  10. OE primary use-cases • Handle cross-compilation. • Handle inter-package dependencies • Must be able to emit packages (tar, rpm, deb, ipk) • Must be able to create images and feeds from packages • Must be highly configurable to support many machines, distribution and architectures. • Writing of metadata must be easy and reusable • Flexibility and power have always been the priorities

  11. OE targets and platforms • Primarely ment for Linux dist • Target processor architectures • ARM, x86, x86-64, PowerPC, MIPS • Distributions • OpenZaurus, Ångström, Familiar, SlugOS • Systems • Wide range, for example BeagleBoard, gumstix

  12. Thankyou

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