# Cross.toml
[target.aarch64-unknown-linux-gnu]
runner = ["qemu-system"]

The above setting is ignored by cross.

As you can see in https://github.com/rust-embedded/cross/blob/8df1f8cd2fe6d09cf312fd4c2cd498499ebc423d/src/docker.rs#L106 and https://github.com/rust-embedded/cross/blob/8df1f8cd2fe6d09cf312fd4c2cd498499ebc423d/src/docker.rs#L176

The CROSS_RUNNER variable is always set to "" in the docker container.

Apparently, the issue was (unintentionally) introduced in #344.