binfmt-dispatcher

binfmt-dispatcher is a simple dispatcher for binfmt_misc that dynamically picks the best interpreter to use at runtime.

Usage

binfmt-dispatcher should be registered as a binfmt_misc handler. If using systemd, this is accomplished via binfmt.d (sample configs are provided for x86 and x86-64). It is recommended to prefix the config with zz- or something akin to ensure it's parsed last, as systemd processes these in lexicographic order. After installing the config, remember to restart systemd-binfmt.service for it to take effect.

binfmt-dispatcher parses configuration from several sources:

• drop-in configs in /usr/lib/binfmt-dispatcher.d/*.toml
• /etc/binfmt-dispatcher.toml
• the running user XDG config (usually $HOME/.config/binfmt-dispatcher/binfmt-dispatcher.toml)

Configs are parsed in order and later settings win. A fully commented config is provided and should be fairly self-explanatory.

When run as an interpreter, binfmt-dispatcher will parse the configs, pick the best interpreter to use based on it and the binary being run, and then run it. If enabled (via the use_muvm config setting), binfmt-dispatcher will use muvm to execute the interpreter in a microVM if the system page-size is not 4k.