About

This work item:

• Aims to add the riscv64-unknown-linux-gnu Rust Language target triplet to the Rust Language github CI runner infrastructure.
• Aims to use the same target platform and target root filesystem assets as used in LR_07_001.
• Aims to use an experimental branch in the upstream CI runner infrastructure. This is expected to be the case until Tier-1 attainment.

Upon successful implementation, the riscv64-unknown-linux-gnu Rust Language target triplet will automatically get tested upon every commit to the Rust Language github repository's main branch. This essentially paves the way for Tier-1 attainment.

Enablement PR: https://github.com/rust-lang/rust/pull/126641

While exploring enablement options, a remote test variant was chosen. This limits testing to "target" support, and skips "host tools" support.

Using Rust's normal testing infrastructure (Docker), the test suite required for a "Tier 1 with Host Tools" test is significantly over 6 hours, even on quite powerful hardware. The Dockerfile tested is located at https://github.com/ferrocene/rust/blob/539c22d365de0839bf3f0c2a27f03f30605236fc/src/ci/docker/host-x86_64/riscv64-gnu/Dockerfile

According to the Target Tier policy (https://doc.rust-lang.org/nightly/rustc/target-tier-policy.html), such long test times alone are enough to disqualify a target from reaching Tier 1.

In the interm, we are pursuing "Tier 1 (without host tools)" which would ensure the target tests (aka the functionality of artifacts produced by the x86_64 platform to be executed on the riscv64gc platform) would pass, without requiring the tools to be passing.

Alongside that work, we are pursuing successful (and fast) full host test suite runs in partnership with https://labs.scaleway.com/en/em-rv1/.