.cargo/config.toml

The .cargo folder in Rust project is optional but important for custom configuration and overrides. It plays different role than Cargo.toml or src/ but is still usefull for more advanced Rust setups.

config.toml

This is the most command file in .cargo folder. You can use it to:

1. Set a custom build target

Useful for cross-compiling

[build]
target = "thumbv7em-none-eabihf"

2. Specify a custom linker

For embedded or non-standard targets

[target.thumbv7em-none-eabihf]
linker = "arm-none-eabi-gcc"

3. Change target directory

Keep build artifacts out of the target/ folder.

[build]
target-dir = "build"

4. Enable or override build scripts

Force features, set environment variables, etc.

[env]
RUSTFLAGS = "-C target-cpu=native"

Example: Embedded Rust Project

[build]
target = "thumbv7em-none-eabihf"

[target.thumbv7em-none-eabihf]
runner = "probe-rs run"
linker = "arm-none-eabi-ld"
rustflags = [
  "-C", "link-arg=-Tlink.x"
]