build: expand SIZE_OPTIMISED_SRC to cover init/config/telemetry paths

[nerdCopter]

AI Generated pull-request

Closes #1221

Change

Adds 41 files to SIZE_OPTIMISED_SRC in make/source.mk, forcing -Os instead of default
optimization on init/config/telemetry paths not on the gyro/PID control loop. Build-flag-only
change — no source logic modified in any listed file.

• Flash drivers (5): drivers/flash.c, drivers/flash_m25p16.c, drivers/flash_w25m.c, drivers/flash_w25n.c, drivers/flash_w25q128fv.c
• Telemetry (12): telemetry/telemetry.c, telemetry/crsf.c, telemetry/ghst.c, telemetry/srxl.c, telemetry/frsky_hub.c, telemetry/hott.c, telemetry/jetiexbus.c, telemetry/smartport.c, telemetry/ltm.c, telemetry/mavlink.c, telemetry/msp_shared.c, telemetry/ibus.c, telemetry/ibus_shared.c
• GPS/navigation (3): io/gps.c, flight/gps_rescue.c, flight/position.c
• Rangefinder (3): drivers/rangefinder/rangefinder_hcsr04.c, drivers/rangefinder/rangefinder_lidartf.c, sensors/rangefinder.c
• Sensor init (3): sensors/initialisation.c, sensors/barometer.c, sensors/compass.c
• Display/IO (10): io/ledstrip.c, io/pidaudio.c, io/rcdevice.c, io/rcdevice_cam.c, io/displayport_max7456.c, io/displayport_msp.c, io/displayport_hdzero_osd.c, io/displayport_oled.c, io/displayport_srxl.c, io/displayport_crsf.c
• CMS menus (2): cms/cms_menu_failsafe.c, cms/cms_menu_gps_rescue.c
• Other (3): sensors/esc_sensor.c, drivers/camera_control.c, io/vtx_beesign.c

All 41 paths verified present in upstream/master @ 7651c15373 by direct filesystem check —
not taken from the issue's original file list, since master may have moved files since filing.

Why these are safe for -Os

Task-rate check in fc/fc_tasks.c: TASK_GPS 100 Hz, TASK_ALTITUDE 40 Hz, TASK_TELEMETRY
250 Hz polling — all well below the gyro/PID hot loop (TASK_GYROPID/TASK_ACC up to 1000 Hz+).
GPS rescue only runs during an active rescue, not steady-state flight. None of the added files
are in SPEED_OPTIMISED_SRC (pid/gyro/imu/mixer/scheduler/rx hot paths, DMA/SPI/timer drivers)
and none overlap with the existing SIZE_OPTIMISED_SRC entries.

findstring-based compile-rule matching checked for accidental substring collisions (e.g.
drivers/flash.c cannot match drivers/flash_m25p16.c — the search requires .c immediately
after flash); none found.

Measured flash/RAM delta

arm-none-eabi-size (xpack GCC 9.3.1, pinned by make/tools.mk), before = upstream/master @
7651c15373, after = this branch. Flash = .text + .data; RAM = .data + .bss.

Target	Flash before	Flash after	Flash Δ	RAM before	RAM after	RAM Δ
HELIOSPRING	380340	372047	-8293 B	112812	112776	-36 B
TMOTORF7	404855	396987	-7868 B	98672	98640	-32 B
MATEKF411	371913	365221	-6692 B	80676	80680	+4 B
WORMFC	381470	374013	-7457 B	97700	97652	-48 B

Flash reduction ~6.7-8.3 KB per target — at/slightly above the issue's own 3-8 KB/512KB-target
estimate. RAM flat, as expected (-Os affects code gen, not data layout).

Build verification

make clean && CCACHE_DISABLE=1 make test: 39/39 unit test binaries PASS, 0 compiler warnings,
0 errors. (One pre-existing, unrelated /usr/bin/ld: ... LOAD segment with RWX permissions
warning appears on host test binaries — confirmed unrelated: src/test/Makefile uses clang
for host tests and does not reference SIZE_OPTIMISED_SRC at all.)

Bench targets (HELIOSPRING TUNERCF405 SKYSTARSF405AIO PYRODRONEF7 FOXEERF722V4 FOXEERF405 APEXF7 TMOTORF7): 8/8 succeeded, 0 warnings, 0 errors, CCACHE_DISABLE=1.

Compile-only targets (MATEKF411 NBDHMBF4PRO WORMFC ALIENWHOOPF7 CRAZYFLIE2): 5/5 succeeded,
0 warnings, 0 errors, CCACHE_DISABLE=1.

Scope note vs. BF 4.5-maintenance

BF 4.5-maintenance's own SIZE_OPTIMISED_SRC (mk/source.mk) is narrower — it does not force
-Os on telemetry, GPS, rangefinder, flash drivers, displayport drivers, ledstrip.c,
pidaudio.c, rcdevice*.c, camera_control.c, or vtx_beesign.c. This change is an
EF-original flash-budget optimization (issue #1221), not a BF-parity backport.

Review status

Local coderabbit review --agent --base upstream/master -c AGENTS.md hit an external rate
limit on first attempt; not re-run before opening this PR. Self-review performed (see above).

Summary by CodeRabbit

• Performance
  • Expanded size-optimized builds to include additional hardware and communication support, including flash storage, telemetry protocols, GPS rescue, rangefinders, sensors, displays, LED and audio controls, camera interfaces, ESC monitoring, and video transmitters.
  • These capabilities are now more consistently available in compact firmware builds.

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📝 Walkthrough

Walkthrough

make/source.mk expands SIZE_OPTIMISED_SRC with additional flash, telemetry, GPS, sensor initialization, display, CMS, ESC sensor, camera, and VTX modules.

Changes

Size-optimized source coverage

Layer / File(s)	Summary
Add cold-path modules to size-optimized builds make/source.mk	Adds flash drivers, telemetry implementations, GPS and rescue code, rangefinder and sensor initialization modules, display and device interfaces, CMS menus, ESC sensor support, camera control, and Beesign VTX sources to SIZE_OPTIMISED_SRC.

Estimated code review effort: 1 (Trivial) | ~5 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the change to expand SIZE_OPTIMISED_SRC for init/config/telemetry paths.
Description check	✅ Passed	The description is detailed and covers the change, rationale, measurements, validation, and issue linkage.
Linked Issues check	✅ Passed	The PR adds the exact cold-path files requested in #1221 and avoids the hot-path categories called out as off-limits.
Out of Scope Changes check	✅ Passed	No unrelated code changes are indicated beyond the requested SIZE_OPTIMISED_SRC build-flag expansion.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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[nerdCopter]

AI generated comment

@coderabbitai review

Local coderabbit review --agent could not complete during implementation — hit persistent free-tier rate-limiting. Change is build-flag-only: 41 files added to SIZE_OPTIMISED_SRC in make/source.mk, no source logic touched. make test 39/39, bench targets 8/8, compile-only targets 5/5, all zero warnings under CCACHE_DISABLE=1. Measured flash savings 6.7-8.3KB across HELIOSPRING/TMOTORF7/MATEKF411/WORMFC, RAM flat. Requesting a full review since no automated review has run on this PR yet.

[coderabbitai]

@nerdCopter: Starting a full review of #1330, including the SIZE_OPTIMISED_SRC changes and their build-rule interactions.

✅ Action performed

Full review finished.