inav/docs/development/Generic_Linux_development.md

Generic Linux development tools

Overview

This article endeavours to provide a generic guide for compiling iNav on Linux for iNav after iNav 2.2.1.

iNav requires a reasonably modern gcc-arm-none-eabi cross-compiler. Different Linux distros will provide different versions of the cross-compiler. This will range from obsolete versions (e.g. Debian, Ubuntu LTS) to the latest stable release (Arch Linux).

In order to provide a uniform and reasonably modern cross compiler, after release iNav 2.2.1, iNav provides for the installation of a "known good / working" cross compiler, as well as a mechanism to override this if your distro provides a more modern option (e.g Arch Linux). In general, from a security perspective, Linux distros discourage the installation of software from sources other than the official distribution repositories and 'approved' sources (Ubuntu PPA, Arch AUR). The iNav approach of providing a recommended compiler is however both sound and justified:

• The cross-compiler is installed from a reputable source (ARM, the company that makes the CPUs used in our UAS)
• Disto cross-compiler are often older than the recommended iNav compiler
• The installed cross-compiler is only used to build iNav and it not obviously / generally available outside of the iNav build environment.

There are a however some specific cases for using the distro cross-compiler in preference to that installed by iNav:

• You are using a distro that installs a more modern compiler (Arch)
• You are using a host platform other than x86_64 (e.g. ia32, AArch64).

However, before we consider the compiler options, it is necessary to install some other dependencies.

Other Prerequisites

In addition to a cross-compiler, it is necessary to install some other tools:

Ubuntu / Debian

$ # make sure the system is updated first
$ sudo apt update && sudo apt upgrade
$ sudo apt install gcc git make ruby curl

Fedora

$ # make sure the system is updated first
$ sudo dnf -y update
$ sudo dnf install gcc git make ruby curl

Arch

$ # make sure the system is updated first
$ sudo pacman -Syu
$ sudo pacman -S gcc git make ruby curl

Once these prerequisites are installed, we can clone the repository to provide a local instance of the iNav source code.

Cloning the repository

$ git clone https://github.com/iNavFlight/inav.git

Note: If you have a Github account with registered ssh key you can replace the git clone command with git clone git@github.com:iNavFlight/inav.git instead of the https link.

The git clone creates an inav directory; we can enter this directory and try and build the firmware. Initially, will probably fail as we have not yet defined the cross-compiler. The following example is from Ubuntu 19.04:

$ cd inav
$ make TARGET=MATEKF405
make/tools.mk:78: *** **ERROR** your arm-none-eabi-gcc is '7.3.1', but '8.2.1' is expected. Override with 'GCC_REQUIRED_VERSION' in make/local.mk or run 'make arm_sdk_install' to install the right version automatically in the tools folder of this repo. Stop.

We must either install the iNav toolchain cross-compiler (preferred option) or define the distro cross-compiler.

Compiler choices

Installing the iNav preferred cross compiler.

In the iNav directory, issue the command make arm_sdk_install. The output will be something like the following (only hopefully you do not suffer from "rural broadband"):

$ make arm_sdk_install
mkdir -p tools
mkdir -p downloads
Warning: Illegal date format for -z, --time-cond (and not a file name).
Warning: Disabling time condition. See curl_getdate(3) for valid date syntax.
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   244  100   244    0     0    645      0 --:--:-- --:--:-- --:--:--   643
100  102M  100  102M    0     0  1385k      0  0:01:15  0:01:15 --:--:-- 1392k

Note that the curl warning will only occur the first time (as there is no pre-existing iNav-specific cross-compiler installed).

Using the Distro compiler.

If your distro provides a more recent cross compiler, or you're using a host platform other than x86_64 you may choose to use your distro compiler (or have no choice in the case of "not x86_64").

You must first install the distro compiler: Arch is the most likely to provide a more modern cross compiler, which would need to be installed as sudo pacman -S arm-none-eabi-gcc arm-none-eabi-binutils arm-none-eabi-newlib.

There are two options to define the distro compiler version:

• Invoke make with the variable GCC_REQUIRED_VERSION set to the distro version. This can be done as:

  $ make GCC_REQUIRED_VERSION=$(arm-none-eabi-gcc -dumpversion)
  

  For convenience, you can create an alias or define a shell function. The shell function will be evaluated each time it is invoked, while the alias will be evaluated once (typically at login), for example:

  # bash function, typically in ~/.bashrc
  $ makefc() { make GCC_REQUIRED_VERSION=$(arm-none-eabi-gcc -dumpversion) $@; }
  export -f makefc
  
  # or, bash alias, typically in ~/.bash_aliases
  $ alias makefc="make GCC_REQUIRED_VERSION=$(arm-none-eabi-gcc -dumpversion) $@"
  

  then e.g $ makefc TARGET=MATEKF405

• or, create the file make/local.mk defining the local distro compiler version.

  $ echo GCC_REQUIRED_VERSION=$(arm-none-eabi-gcc -dumpversion) > make/local.mk
  

  then use make normally, $ make TARGET=MATEKF405

If you define the distro cross-compiler version in make/local.mk, you will need to update make/local.mk whenever your disto updates the cross-compiler.

Building the firmware

By default, make builds the REVO target, to build another target, specify the target name to the make command, for example:

make TARGET=MATEKF405

The resultant hex file are in the obj/ directory.

You can use the INAV Configurator to flash the local obj/inav_TARGET.hex file, or use stm32flash or dfu-util directly from the command line.

msp-tool and flash.sh provide / describe 3rd party helper tools for command line flashing.

Updating and rebuilding

In order to update your local firmware build:

• Navigate to the local iNav repository
• Use the following steps to pull the latest changes and rebuild your local version of iNav:

$ cd inav
$ git pull
$ make TARGET=<TARGET>

Advanced Usage

For more advanced development information and git usage, please refer to the development guide.