zephyr

History

Carles Cufi fc3c2c0abb samples: basic: Add a minimal sample Add a minimal sample that showcases minimal ROM sizes. It can be built in several configurations, all very restrictive when it comes to features enabled in order to verify the fact that we can fit in small devices and to be able to accurately measure the sizes of the kernel's basic features. Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>		2019-05-15 10:44:59 +02:00
..
src	…
CMakeLists.txt	…
README.rst	…
arm.conf	…
common.conf	…
mt.conf	…
no-mt.conf	…
no-preempt.conf	…
no-timers.conf	…
sample.yaml	…
x86.conf	…

README.rst

.. _minimal_sample:

Minimal sample
##############

Overview
********

This sample defines An empty ``main()`` and a set of minimal configurations
that provide tests for the smallest ROM sizes possible with the Zephyr kernel.

The following configuration files are available:

* :file:`mt.conf`: Enable multithreading
* :file:`no-mt.conf`: Disable multithreading
* :file:`no-preempt.conf`: Disable preemption
* :file:`no-timers.conf`:: Disable timers
* :file:`arm.conf`: Arm-specific disabling of features

Building and measuring ROM size
*******************************

In order to compare ROM sizes with different minimal configurations, the
following combinations are suggested:

* Reel board (Arm architecture)

  * Multithreading enabled

    * Reference ROM size: 7-8KB

    .. zephyr-app-commands::
       :zephyr-app: samples/basic/minimal
       :tool: west
       :host-os: unix
       :board: reel_board
       :build-dir: reel_board/mt/
       :conf: "common.conf mt.conf arm.conf"
       :goals: rom_report
       :compact:

  * Multithreading enabled, no preemption

    * Reference ROM size: 7-8KB

    .. zephyr-app-commands::
       :zephyr-app: samples/basic/minimal
       :tool: west
       :host-os: unix
       :board: reel_board
       :build-dir: reel_board/mt-no-preempt/
       :conf: "common.conf mt.conf no-preempt.conf arm.conf"
       :goals: rom_report
       :compact:

  * Multithreading enabled, no preemption, timers disabled

    * Reference ROM size: 3-4KB

    .. zephyr-app-commands::
       :zephyr-app: samples/basic/minimal
       :tool: west
       :host-os: unix
       :board: reel_board
       :build-dir: reel_board/mt-no-preempt-no-timers/
       :conf: "common.conf mt.conf no-preempt.conf no-timers.conf arm.conf"
       :goals: rom_report
       :compact:

  * Multithreading disabled, timers enabled

    * Reference ROM size: 4-5KB

    .. zephyr-app-commands::
       :zephyr-app: samples/basic/minimal
       :tool: west
       :host-os: unix
       :board: reel_board
       :build-dir: reel_board/no-mt/
       :conf: "common.conf no-mt.conf arm.conf"
       :goals: rom_report
       :compact:

  * Multithreading disabled, timers disabled

    * Reference ROM size: 2-3KB

    .. zephyr-app-commands::
       :zephyr-app: samples/basic/minimal
       :tool: west
       :host-os: unix
       :board: reel_board
       :build-dir: reel_board/no-mt-no-timers/
       :conf: "common.conf no-mt.conf no-timers.conf arm.conf"
       :goals: rom_report
       :compact: