LXA TAC System Daemon

This piece of software provides an interface between the hardware of the Linux Automation GmbH Test Automation Controller (LXA TAC) and the user. It runs the interface on the TACs LCD display, as well as the web server. The web server provides an interactive web interface as well as an API for scripting purposes.

Building outside of meta-lxatac

We will first have a look on how to build the tacd for your host PC, as it is easier than building for the LXA TAC itself, then we will go into how to build for the real hardware.

General Setup

Install rust and cargo

We do not require a particularly recent version of Rust, so you may have some luck installing rust and cargo from your distribution's package repositories. If not you may have to resort to installing via rustup (which may also be available from distribution repositories).

Install npm

We use npm to build the LXA TAC web interface. You may again have some luck installing it from distribution repositories or have to resort to installing via curl … | sh as documented in the README linked above.

Build web interface

The tacd serves a React-Based web interface to interactively remote control the LXA TAC. If you want to use this web interface with your tacd build you should build it from source using the dark witchcraft that is javascript dependency management:

$ cd web
$ npm install .
$ npm run build

Building for your PC

The tacd contains stubs that make building a stripped-down version for your host PC possible. These can be useful for quickly checking if a change compiles, testing changes in the web interface or running unit tests.

Run tacd on your PC

The tacd heavily relies on a lot of hardware and files being present on the TAC, this means that the full tacd can not run on a non-TAC system.

You can however run a stripped-down version by using:

$ cargo run --features=demo_mode --no-default-features

Note that rust will complain very loudly about a lot of dead code, which is not used when building for PC but used on the TAC.

Unit tests

While the test coverage is not great yet (PRs welcome!) there are some unit tests that can help find regressions. Run them using:

$ cargo test --no-default-features

Build tacd for the TAC

To cross-compile for the LXA TAC you will need to build and install a cross SDK. If you only want to test a little patch it may be easier to use the yocto devtool in meta-lxatac, instead, which does however have the drawback of longer build times.

Add rust toolchain

To build outside of meta-lxatac you first need to install the respective rust toolchain:

$ rustup target add armv7-unknown-linux-gnueabihf

Install the SDK

Next you will have to build an SDK using meta-lxatacthat includes libiio:

$ bitbake -c do_populate_sdk lxatac-core-image-iio

And install it on your host PC.

To build using the SDK you will have to souce it according to the yocto SDK documentation and add the following to the .cargo/config.toml:

[target.armv7-unknown-linux-gnueabihf]
linker = "[PATH_TO_YOUR_INSTALLED_SDK]/sysroots/x86_64-oesdk-linux/usr/bin/arm-oe-linux-gnueabi/arm-oe-linux-gnueabi-gcc"
rustflags = [
    "-C", "link-arg=-mthumb",
    "-C", "link-arg=-mfpu=neon-vfpv4",
    "-C", "link-arg=-mfloat-abi=hard",
    "-C", "link-arg=-mcpu=cortex-a7",
    "-C", "link-arg=--sysroot=[PATH_TO_YOUR_INSTALLED_SDK]/sysroots/cortexa7t2hf-neon-vfpv4-oe-linux-gnueabi",
]

Remember to update both paths so that they point to your installed SDK. Also remember to always source the SDK activation script before building for the LXA TAC (and using a shell without a sourced SDK when building for the host PC).

Building

Then, you can use cargo build --target armv7-unknown-linux-gnueabihf to compile the tacd. The resulting binary is placed in target/armv7-unknown-linux-gnueabihf/release/tacd and contains everything required to run the tacd, including the web interface. It can thus just be copied to your LXA TAC and run instead of the existing tacd (remember to systemctl stop tacd the already running instance).

Contributing

We are always open for outside contributions, just make sure to follow these guidelines:

• Use a somewhat recent stable rust release for testing
• Use cargo fmt after every change to the rust codebase
• Use cargo deny check license if you have introduced new dependencies to check if they (or their dependencies) introduce license issues.
• Use npx prettier@=3.0.1 --write . (in the web directory) after every change to the web codebase.