Nuno Marques
fd61773e6f
Two cosmetic-but-noisy errors at every SITL boot once the rcS runs via
the portable /bin/sh backend (this branch's commit 9abb4ac867). On
ROS Integration Tests the container ships without bc, so the
PX4_SIM_SPEED_FACTOR multiplications fail and rcS emits:
px4-rc: 190: etc/init.d-posix/rcS: bc: not found
COM_DL_LOSS_T set to
ERROR [param] not enough arguments.
Try 'param set COM_DL_LOSS_T 3 [fail]'
(The ros_test_runner.py path always sets PX4_SIM_SPEED_FACTOR=1, so
the bc block always runs even though the multiplication is a no-op.)
Substitute awk -v s="$SF" 'BEGIN{print s*N}' for the bc one-liners.
awk is in coreutils on every PX4 dev / CI image and produces identical
floating-point output; bc is not packaged in the ROS Integration
container.
Separately, every external param-set call from the rcS races the
daemon's closesocket() and the client's recv() picks up ECONNRESET
(or EPIPE) instead of a clean EOF, even though the {0, retval}
sentinel is already buffered. The Linux #else branch unconditionally
logged "unable to read from socket" and returned -1, drowning the rcS
output in spurious errors:
EKF2_EV_CTRL: curr: 0 -> new: 15
ERROR [px4_daemon] unable to read from socket
Mirror the Windows WSAECONNRESET / WSAESHUTDOWN handling on Linux:
when errno is ECONNRESET / EPIPE and the sentinel is buffered, honour
it as end-of-stream instead of treating the close race as a failure.
Also append strerror(errno) to the surviving error path so a real
socket failure (EBADF, EINTR, ENOMEM, ...) still surfaces with the
underlying cause.
Both fixes are no-ops on the happy path; they only suppress error
output that the daemon-client teardown race emits during normal
shutdown.
Signed-off-by: Nuno Marques <n.marques21@hotmail.com>
The autopilot stack the industry builds on.
About
PX4 is an open-source autopilot stack for drones and unmanned vehicles. It supports multirotors, fixed-wing, VTOL, rovers, and many more experimental platforms from racing quads to industrial survey aircraft. It runs on NuttX, Linux, and macOS. Licensed under BSD 3-Clause.
Why PX4
Modular architecture. PX4 is built around uORB, a DDS-compatible publish/subscribe middleware. Modules are fully parallelized and thread safe. You can build custom configurations and trim what you don't need.
Wide hardware support. PX4 runs on a wide range of autopilot boards and supports an extensive set of sensors, telemetry radios, and actuators through the Pixhawk ecosystem.
Developer friendly. First-class support for MAVLink and DDS / ROS 2 integration. Comprehensive SITL simulation, hardware-in-the-loop testing, and log analysis tools. An active developer community on Discord and the weekly dev call.
Vendor neutral governance. PX4 is hosted under the Dronecode Foundation, part of the Linux Foundation. Business-friendly BSD-3 license. No single vendor controls the roadmap.
Supported Vehicles
 Multicopter |
 Fixed Wing |
 VTOL |
 Rover |
…and many more: helicopters, autogyros, airships, submarines, boats, and other experimental platforms. These frames have basic support but are not part of the regular flight-test program. See the full airframe reference.
Try PX4
Run PX4 in simulation with a single command. No build tools, no dependencies beyond Docker:
docker run --rm -it -p 14550:14550/udp px4io/px4-sitl:latest
Open QGroundControl and fly. See PX4 Simulation Quickstart for more options.
Build from Source
git clone https://github.com/PX4/PX4-Autopilot.git --recursive
cd PX4-Autopilot
make px4_sitl
Note
See the Development Guide for toolchain setup and build options.
Documentation & Resources
| Resource | Description |
|---|---|
| User Guide | Build, configure, and fly with PX4 |
| Developer Guide | Modify the flight stack, add peripherals, port to new hardware |
| Airframe Reference | Full list of supported frames |
| Autopilot Hardware | Compatible flight controllers |
| Release Notes | What's new in each release |
| Contribution Guide | How to contribute to PX4 |
Community
- Weekly Dev Call — open to all developers (Dronecode calendar)
- Discord — Join the Dronecode server
- Discussion Forum — PX4 Discuss
- Maintainers — see
MAINTAINERS.md - Contributor Stats — LFX Insights
Contributing
We welcome contributions of all kinds — bug reports, documentation, new features, and code reviews. Please read the Contribution Guide to get started.
Citation
If you use PX4 in academic work, please cite it. BibTeX:
@software{px4_autopilot,
author = {Meier, Lorenz and {The PX4 Contributors}},
title = {{PX4 Autopilot}},
publisher = {Zenodo},
doi = {10.5281/zenodo.595432},
url = {https://px4.io}
}
The DOI above is a Zenodo concept DOI that always resolves to the latest release. For a version-pinned citation, see the Zenodo record or our CITATION.cff.
Governance
The PX4 Autopilot project is hosted by the Dronecode Foundation, a Linux Foundation Collaborative Project. Dronecode holds all PX4 trademarks and serves as the project's legal guardian, ensuring vendor-neutral stewardship — no single company owns the name or controls the roadmap. The source code is licensed under the BSD 3-Clause license, so you are free to use, modify, and distribute it in your own projects.
