Running Checks Across Architectures

just preflight runs one CI lane locally. Without platform=, that’s the host lane: lint, check, unittests, miri, loom, selftests, and the audit / license group. With platform=X, it’s the X lane: lint and check at X, plus the universal audit group. Unit, miri, and loom tests are host-only by construction (they declare target_compatible_with = [host_configuration.os, host_configuration.cpu]) and --skip-incompatible-targets drops them silently under platform=X. selftests always boots the riscv64 qemu image; per-arch qemu_test targets aren’t wired yet.

just preflight                                 # full host lane
just platform=//platforms:riscv64 preflight    # riscv64 lane
just platform=//platforms:aarch64 preflight    # aarch64 lane
just platform=//platforms:x86_64  preflight    # x86_64 lane

The same platform= flag is accepted by check, clippy, doc, unittests, miri, loom, and benchmark if you want to invoke a single phase. CI matrixes check, clippy, and selftests across the supported arches on every push; the host lane additionally runs unittests, miri, loom, and the audit group.

A crate that’s intrinsically host-only (test runners, benches, fuzzers, host tooling like mkdisk-img) declares this with target_compatible_with:

load("@prelude//platforms:defs.bzl", "host_configuration")

rust_test(
    name = "my_unittests",
    srcs = glob(["src/**/*.rs"]),
    target_compatible_with = [host_configuration.os, host_configuration.cpu],
    visibility = ["PUBLIC"],
)

The rust_benchmark, rust_loom_test, and rust_fuzz wrappers in build/{bench,loom,fuzz}.bzl apply this automatically. A crate that’s arch-locked (e.g. lib/riscv, the kernel, the loader) declares the inverse:

target_compatible_with = ["prelude//cpu/constraints:riscv64"],