Cross-Compiling Veloren

As more and more people want to play or develop for Veloren on other platforms, it may come as no surprise that building on these platforms might not be the most elegant solution, emulation is quite often slow, and the platform of choice simply doesn't have the necessary resources to build the game in a reasonable amount of time.

Please note: Documentation of these steps is currently underway, you might need to adjust these for your specific scenario.

Linux

Prerequisites

In order to build for your platform of choice, for example arm64, you'll need to install the compiler toolchain for that architecture. In our case, that's aarch64-linux-gnu-gcc.

You'll also need the compilation dependencies of the project installed for your architecture. In our example, we used a Raspberry Pi to install all dependencies needed for compiling the project, then the SD Card was plugged into the building system, and it's root filesystem was mounted under /mnt.

Cross-Compiling

The project source tree was cloned to our building machine, in an arbitrary location. Open a terminal and move to the project root, then execute:

rustup target add [target]

where [target] is one of the targets from here. In our case, that was aarch64-unknown-linux-gnu. After this, you'll need to go in the newly created .cargo directory and edit the config file. Add the following entry:

[target.X]
linker="Y"

where X was aarch64-unknown-linux-gnu in our case, and Y was aarch64-linux-gnu-gcc respectively. These should correspond with the target mentioned above, and the compiler toolchain respectively (the one you installed as a prerequisite).

For the compilation itself, you'll need to tell Cargo where the correct libraries are. Given that we've mounted the root filesystem of our target at /mnt, we can use the PKG_CONFIG_SYSROOT_DIR environment variable.

The compilation command looks like this:

PKG_CONFIG_SYSROOT_DIR=Z cargo build --release --target X

where X is the target we're building for, and Z is the filesystem root of the platform we're building for. This is where the Raspberry Pi's SD Card was mounted, in our case /mnt.

Feel free to adjust the command for your needs, as per the original compilation instructions. You should find the built binaries in the target subfolder of the project root.

Note

At the time of writing, there is an issue with the keyboard-keynames library for aarch64 and probably others too. Assuming ~/.cargo is the default location of your Cargo downloads, edit the file located at: ~/.cargo/git/checkouts/keyboard-keynames-0b8339ee617b0344/a97ae50/src/platform/unix/key_layout.rs and replace all instances of

unsafe { &*(utf_key as *const [i8] as *const [u8]) }

with

unsafe { &*(utf_key as *const [c_char] as *const [u8]) }

after which compilation should succeed.