.. _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
: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
: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
: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
: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
: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:
afcbc9992c