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Uses old Rust 2015

0.0.8 Jan 15, 2024
0.0.7 Jan 5, 2024
0.0.6 Apr 3, 2023
0.0.4 Mar 31, 2023

#1011 in Development tools

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527 lines

crit: Rust cross-compiler

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crit compiles Rust application ports for many different target platforms. This effort is based on conventional Rust tooling, including cross, cargo, and the amazing rustc compiler.


$ cd example

$ crit

$ ls .crit/bin

By default, crit builds in release mode (-- -r).

See crit -h for more options.








$ cargo install --force --path .




  • a host capable of running musl/Linux containers (e.g. a GNU/Linux, musl/Linux, macOS, or Windows host)
  • Docker First Aid Kit
  • Apply DOCKER_DEFAULT_PLATFORM = linux/amd64 environment variable
  • ASDF 0.10 (run asdf reshim after each Rust application binary installation)
  • cargo-cache
  • direnv 2
  • POSIX compatible tar
  • tinyrick 0.0.9
  • tree
  • GNU compatible time
  • Amphetamine (macOS), The Caffeine (Windows), Caffeine (Linux) can prevent hibernation during any long builds
  • a UNIX environment, such as macOS, Linux, BSD, WSL, etc.

tar is a portable archiver suitable for creating *.tgz tarball archives. Users can then download the tarball and extract the executable relevant to their platform. Tarballs are especially well suited for use in Docker containers, as the tar command is more likely to be installed than unzip.

Note that non-UNIX file systems may not preserve crucial chmod acl bits during port generation. This can corrupt downstream artifacts, such as compressed archives and installation procedures.


For more details on developing crit itself, see DEVELOPMENT.md.


Help, some targets are broken?

Check that your project is able to build with conventional cross or cargo commands against a single target. A project that does not compile against a single target, will naturally have difficulty when attempting to cross-compile for multiple targets.

Note that Rust introduces new, under-supported targets all the time. We try to keep up, but sometimes we miss a few of these. Regardless, you can declare which targets are disabled, by writing a custom pattern for the -e / --exclude-targets flag.

Some targets may lack stock support for the Rust std library. This is common for bare metal or embedded targets. For these kinds of targets, you have several strategies for resolution:

  • Provide a std implementation. Reach out to specialists for the specific target involved.
  • Avoid using the std library, in both your code, as well as the dependency tree. This is actually common practice for many Rust projects, as an proactive stance on embedded development support.
  • Disable undesired targets.

Help, cross-compilation appears frozen?

crit hides a lot of compiler noise. While a target is building, you can use common Docker commands to inspect the compilation process:

  • docker ps -a
  • docker logs [--follow] <container id>

Help, cross-compilation is slow?

Yes, it sure is! Almost as slow as using Virtual Machines for cross-compilation.

Rustaceans come to expect that the Rust compiler is analytical, spending more time optimizing programs, so that the final binaries will run safer and faster. The Rust compiler often taking a long time to compile each individual target.

Naturally, when cross-compiling multiple targets, that time multiplies by the number of targets.

Some cross-compilation performance tips:

  • Tune your Docker setup (see the Docker First Aid Kit above)
  • Reset common Cargo build profile options (codegen-units, lto, strip, etc.)
  • Use debug mode (e.g., --)
  • Use fewer dependencies
  • Design with the UNIX Philosophy, namely Make each program do one thing well. Not a hundred features poorly.
  • Keep the host awake (see Amphetamine / The Caffeine / Caffeine above)
  • Reserve cross-compilation as a release-time step, distinct from more rapid development tasks
  • Perform cross-compilation in a CI/CD pipeline with more CPU, disk, and RAM resources
  • Exclude more targets (e.g., -e <target pattern>)


  • cross underlying cross-compiler system
  • cross-toolchains provisions cross Docker images
  • cubejs/rust-cross Docker images for additional cross targets
  • factorio generates Go application ports based on the standard Go toolchain
  • tug automates multi-platform Docker image builds
  • WASM provides a portable interface for C/C++ code.
  • xgo supports Go projects with native cgo dependencies.


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