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t27b: the first self-built module -- a plan spec compiled by t27b, linked into t27b instead of gen-rust #8949
Description
Step 3c of the matryoshka (see #8920). Choose one pure plan module (for example cmp_op or literal_plan). Instead of mounting gen/rust/tri/t27b/<plan>.rs from t27c gen-rust, compile specs/tri/t27b/<plan>.t27 with t27b into an ELF object on the lab and link it into the t27b binary through the bridge (step 3b).
Acceptance:
- t27b built that way passes cargo test.
- The lab's signed receipt compare against the previous master is EQUIVALENT.
- No Rust stands between that spec and the AArch64 that t27b runs.
User Scenarios
- Given a t27b build that currently uses a Rust-generated plan module (e.g.,
cmp_op) fromgen/rust/tri/t27b/cmp_op.rs, When the build is changed to compilespecs/tri/t27b/cmp_op.t27with t27b into an ELF object and link it via the bridge, Then t27b builds and passescargo testwith no Rust code between the spec and the AArch64 execution.
Requirements
- FR-001: The plan spec
specs/tri/t27b/cmp_op.t27MUST be compiled by t27b into an ELF object file on the lab. - FR-002: The ELF object MUST be linked into the t27b binary through the bridge (step 3b) replacing the Rust-generated module.
- FR-003: The t27b binary built this way MUST pass
cargo test(exit 0). - FR-004: The lab's signed receipt for the new build MUST compare as EQUIVALENT to the previous master receipt.
Success Criteria
cargo test -p t27bexits withexit 0.- The lab receipt comparison command outputs
EQUIVALENT. - The file
specs/tri/t27b/cmp_op.t27exists and is a valid t27 spec. - The file
gen/rust/tri/t27b/cmp_op.rsis no longer used in the t27b build (removed or excluded). - The bridge linking step in
scripts/tri_loop/t27b.pyincludes the new ELF object.
Boundary
- specs/tri/t27b/cmp_op.t27
- gen/rust/tri/t27b/cmp_op.rs
- scripts/tri_loop/t27b.py
- compiler/cli/spec.t27
Activity
PHI LOOP: open the active cell on epic #8951, t27b builds itself (Closes
gHashTag commentedon Oct 11, 2026
Design decision (owner delegated the choice on 2026-10-11, "do what is best for us"): link self-built modules through bootstrap stages, with no build.rs and no own-language exception.
specs/tri/t27b/*_plan.t27, starting with one pure plan such as cmp_op) into ELF objects viat27b build --elf(t27b: ELF64 relocatable objects for aarch64 Linux, written in t27 -- specs/tri/t27b/elf.t27 (Closes #8947) #8955), with the C ABI from t27b: a C-ABI bridge -- Rust calls t27b-built fns through extern "C" under AAPCS64 (Closes #8948) #8983, and archives them (ar).extern "C"block with#[link(name = ..., kind = "static")]replaces the#[path]mount. The link search path comes from the stage driver asRUSTFLAGS=-L native=<dir>, so there is no .cargo/config.toml and no build.rs.cargo build, so contributors' builds keep working.Proof for 3c:
This stage structure is the same one #8950 needs for the fixed point (stage2 == stage3). Prerequisites from the #8983 report:
pubfns, or make spliced plan fns local symbols;Scheduled after the weekly budget reset (2026-10-17).