Cross-compiling

Contower supports cross-compiling, allowing users to run a binary on one platform (e.g., aarch64) that was compiled on another platform (e.g., x86_64).

Instructions

Cross-compiling requires Docker, rustembedded/cross, and for the current user to be in the Docker group.

The binaries will be created in the target/ directory of the Contower project.

Checking Docker Group Membership

To ensure you have the necessary permissions to run Docker commands without using sudo, follow these steps to check if you are already in the Docker group:

Open your terminal.
Type the following command:
```
groups
```
Look for docker in the list of groups displayed. If docker is listed, you are already in the Docker group and no further action is needed.

If you are not in the Docker group, follow the steps below to add yourself to the Docker group.

Adding User to Docker Group

To run Docker commands without sudo, add your user to the Docker group:

Create the Docker group (if it doesn't already exist):
```
sudo groupadd docker
```
Add your user to the Docker group:
```
sudo usermod -aG docker $USER
```
Restart the Docker service:
```
sudo systemctl restart docker
```
Log out and log back in so that your group membership is re-evaluated, or you can use:
```
newgrp docker
```

After following these steps, you will be able to run Docker commands without needing to prepend them with sudo.

Targets

The Makefile in the project contains four targets for cross-compiling:

build-x86_64: builds an optimized version for x86_64 processors (suitable for most users).
build-x86_64-portable: builds a version for x86_64 processors which avoids using some modern CPU instructions that are incompatible with older CPUs.
build-aarch64: builds an optimized version for 64-bit ARM processors (suitable for Raspberry Pi 4).
build-aarch64-portable: builds a version for 64-bit ARM processors which avoids using some modern CPU instructions. In practice, very few ARM processors lack the instructions necessary to run the faster non-portable build.

For more information about optimized vs portable builds see Portability.

Example

cd contower
make build-aarch64

The contower binary will be compiled inside a Docker container and placed in contower/target/aarch64-unknown-linux-gnu/release.

Feature Flags

We are still working on this feature.

Compilation Profiles

We are still working on this feature.

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