Binary Size Profiling

The bloaty_compare_master build target allows you to get a better understanding of the impact of changes on code size. When it is used, the toolchain downloads the latest successful master build of a particular firmware and compares it to the local build (using the bloaty size profiler for binaries).

:::tip This can help analyse changes that (may) cause px4_fmu-v2_default to hit the 1MB flash limit. :::

Bloaty must be in your path and found at cmake configure time. The PX4 docker files install bloaty as shown:

sh git clone --recursive https://github.com/google/bloaty.git /tmp/bloaty \ && cd /tmp/bloaty && cmake -GNinja . && ninja bloaty && cp bloaty /usr/local/bin/ \ && rm -rf /tmp/*

The example below shows how you might see the impact of removing the mpu9250 driver from px4_fmu-v2_default. First it locally sets up a build without the driver:

sh % git diff diff --git a/boards/px4/fmu-v2/default.px4board b/boards/px4/fmu-v2/default.px4board index 40d7778..2ce7972 100644 --- a/boards/px4/fmu-v2/default.px4board +++ b/boards/px4/fmu-v2/default.px4board @@ -36,7 +36,7 @@ - CONFIG_DRIVERS_IMU_INVENSENSE_MPU9250=y + CONFIG_DRIVERS_IMU_INVENSENSE_MPU9250=n

Then use the make target, specifying the target build to compare (px4_fmu-v2_default in this case):

sh % make px4_fmu-v2_default bloaty_compare_master ... ... ... VM SIZE FILE SIZE -------------- -------------- [DEL] -52 MPU9250::check_null_data(unsigned int*, unsigned char) -52 [DEL] [DEL] -52 MPU9250::test_error() -52 [DEL] [DEL] -52 MPU9250_gyro::MPU9250_gyro(MPU9250*, char const*) -52 [DEL] [DEL] -56 mpu9250::info(MPU9250_BUS) -56 [DEL] [DEL] -56 mpu9250::regdump(MPU9250_BUS) -56 [DEL] ... -336 [DEL] [DEL] -344 MPU9250_mag::_measure(ak8963_regs) -344 [DEL] [DEL] -684 MPU9250::MPU9250(device::Device*, device::Device*, char const*, char const*, cha -684 [DEL] [DEL] -684 MPU9250::init() -684 [DEL] [DEL] -1000 MPU9250::measure() -1000 [DEL] -41.3% -1011 [43 Others] -1011 -41.3% -1.0% -1.05Ki [Unmapped] +24.2Ki +0.2% -1.0% -10.3Ki TOTAL +14.9Ki +0.1%

This shows that removing mpu9250 from px4_fmu-v2_default would save 10.3 kB of flash. It also shows the sizes of different pieces of the mpu9250 driver.