linxisa/linx-skills/linx-lib

Linx Lib

Overview

Use this skill for combined libc bring-up and runtime policy across lib/glibc and lib/musl.

Gate ladder

• glibc:
• G1a configure + csu/subdir_lib
• G1b shared libc.so gate
• musl:
• M1/M2/M3 build gates
• R1/R2 runtime gates

Canonical commands

bash /Users/zhoubot/linx-isa/lib/glibc/tools/linx/build_linx64_glibc.sh
MODE=phase-b /Users/zhoubot/linx-isa/lib/musl/tools/linx/build_linx64_musl.sh
QEMU=/Users/zhoubot/linx-isa/emulator/qemu/build-linx/qemu-system-linx64 \
  python3 /Users/zhoubot/linx-isa/avs/qemu/run_musl_smoke.py --mode phase-b --link static
QEMU=/Users/zhoubot/linx-isa/emulator/qemu/build-linx/qemu-system-linx64 \
  python3 /Users/zhoubot/linx-isa/avs/qemu/run_musl_smoke.py --mode phase-b --link shared
QEMU=/Users/zhoubot/linx-isa/emulator/qemu/build-linx/qemu-system-linx64 \
  python3 /Users/zhoubot/linx-isa/avs/qemu/run_musl_smoke.py --mode phase-b --link both --sample all

Runtime policy

• Static and shared outcomes are first-class and separate.
• No aggregate green if one mode fails.
• Bind runtime evidence to the current build-linx QEMU explicitly; do not let

the runner fall back to a stale emulator/qemu/build binary.

• If the mandatory call/ret cross-stack audit fails before samples start,

report every sample as BLOCKED_PRE_RUN, not as a libc runtime failure.

• Preserve mode-level logs and summaries.
• PR/runtime gate runs use --sample all so fork/wait, fork/exec, stdio, and

C++ startup regressions are not hidden behind the lightweight malloc/printf default. Use narrower --sample selections only for local triage.

• Treat phase-b runtime proof and hosted phase-c packaging proof separately.

SPEC Stage-A and other hosted-userland lanes need the shared-musl runtime package (libc.so and loader path), so do not claim hosted closure from phase-b static/shared smoke results alone.

• A gfrun-hosted SMT4 ELF must not enter libc startup on all four PEs. PE0

owns _start, libc/TLS, file descriptors, and process exit; PE1 through PE3 use an independent-stack lightweight entry and no libc/syscall ABI.

• The first lightweight ABI is static-only and single-shot. The ELF exports

__linx_group_worker_start plus a directly called __linx_group_worker_main(pe_id, context). Missing worker symbols and PT_INTERP images fail closed before guest execution. Static PIE with PT_DYNAMIC but no PT_INTERP remains a static lane.

• In this hosted group lane, PE0 SYS_exit and SYS_exit_group both terminate

the core; a non-leader SYS_exit remains per-PE. This accommodates current Linx musl exit ordering without giving workers process ownership.

• Keep ownership split: Linx-TileOP-API owns the public header and ABI docs;

compiler-rt owns linx/group_runtime.c; libc/toolchain packaging installs it in liblinx_builtin_rt.a; workloads define only __linx_group_worker_main and consume the archive.

Alignment checks

• ABI/register conventions align with Linux UAPI.
• Relocation IDs/contracts align across libc + linker + kernel.
• signal/ucontext/setjmp behavior is cross-stack consistent.
• glibc and musl dynamic loaders enforce the same .note.pto.isa identity on

the main executable, every DT_NEEDED object, and every dlopen object. Owner is PTO\0, type is 1, alignment is four bytes, and the compact JSON descriptor has no trailing NUL; missing, old, and mismatched identities are rejected before constructors or application code run.

Skill evolve loop (mandatory closeout)

• At closeout, decide skill-evolve: update or skill-evolve: no-update.
• Update this skill only for material reusable findings:
• new libc/runtime contract required by gates,
• new mandatory build/runtime command/env for reproducible results,
• new recurring triage flow for static/shared divergences.
• Do not update for minor optimization, wording cleanup, or one-off local workaround.
• If update is needed, validate with:
• python3 /Users/zhoubot/.codex/skills/.system/skill-creator/scripts/quick_validate.py /Users/zhoubot/linx-isa/skills/linx-skills/linx-lib
• python3 /Users/zhoubot/linx-isa/skills/linx-skills/scripts/check_skill_change_scope.py --repo-root /Users/zhoubot/linx-isa/skills/linx-skills --base origin/main

Included scope

This consolidated skill absorbs prior glibc-bringup, musl-bringup, and libc-focused call/ret runtime checks.

References

• references/gates_and_policy.md