Minimal footprint

Overview

This sample provides an empty main() and various configuration files that can be used to measure Zephyr’s minimal ROM footprint in different configurations.

The following configuration files are available:

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

Building and measuring ROM size

The following combinations are suggested for comparing ROM sizes in different configurations. They all target the reel board (Arm Aarch32 architecture).

Multithreading enabled

Reference ROM size: 7-8KB

west build -b reel_board -d build/reel_board/mt samples/basic/minimal -- -DCONF_FILE="common.conf mt.conf arm.conf"
west build -t rom_report -d build/reel_board/mt

Multithreading enabled, no preemption

Reference ROM size: 7-8KB

west build -b reel_board -d build/reel_board/mt-no-preempt samples/basic/minimal -- -DCONF_FILE="common.conf mt.conf no-preempt.conf arm.conf"
west build -t rom_report -d build/reel_board/mt-no-preempt

Multithreading enabled, no preemption, timers disabled

Reference ROM size: 3-4KB

west build -b reel_board -d build/reel_board/mt-no-preempt-no-timers samples/basic/minimal -- -DCONF_FILE="common.conf mt.conf no-preempt.conf no-timers.conf arm.conf"
west build -t rom_report -d build/reel_board/mt-no-preempt-no-timers

Multithreading disabled, timers enabled

Reference ROM size: 4-5KB

west build -b reel_board -d build/reel_board/no-mt samples/basic/minimal -- -DCONF_FILE="common.conf no-mt.conf arm.conf"
west build -t rom_report -d build/reel_board/no-mt

Multithreading disabled, timers disabled

Reference ROM size: 2-3KB

west build -b reel_board -d build/reel_board/no-mt-no-timers samples/basic/minimal -- -DCONF_FILE="common.conf no-mt.conf no-timers.conf arm.conf"
west build -t rom_report -d build/reel_board/no-mt-no-timers