Build Fix: Avoid invalid make -j 0 in NCCL EP submodule build

[phu0ngng]

Description

Avoid invalid make -j 0 in NCCL EP submodule build

Type of change

• Documentation change (change only to the documentation, either a fix or a new content)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Infra/Build change
• Code refactoring

Checklist:

• I have read and followed the contributing guidelines
• The functionality is complete
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[phu0ngng]

/te-ci L0

[jberchtold-nvidia]

LGTM pending CI, thanks!

[greptile-apps]

Greptile Summary

This PR fixes a build failure in the NCCL EP submodule build step where make -j 0 was being passed when no explicit job limit was configured. make -j 0 is invalid in GNU make; the fix replaces the two-argument form ("-j", str(nproc)) with a single combined flag (-j{nproc}) when nproc > 0, or just -j (unlimited parallelism) when nproc == 0 (the default from get_max_jobs_for_parallel_build()).

• Replaces ["make", "-j", str(nproc), ...] with make_jobs = f"-j{nproc}" if nproc else "-j" to produce valid make invocations in all cases.
• The else "-j" branch is reachable: get_max_jobs_for_parallel_build() defaults to 0 when no NVTE_BUILD_MAX_JOBS, MAX_JOBS, or --parallel= argument is provided, making nproc falsy and triggering unlimited parallelism as intended.

Confidence Score: 5/5

Safe to merge — a minimal, targeted fix to a build-time subprocess invocation with no runtime or API surface changes.

The change is a single-line fix that replaces an invalid make -j 0 call (which causes build failures when no explicit job limit is configured) with a correctly formed make -j or make -jN invocation. The logic maps cleanly to get_max_jobs_for_parallel_build()'s documented return values, the else "-j" branch is genuinely reachable, and no other code paths are affected.

No files require special attention.

Important Files Changed

Filename	Overview
setup.py	Minimal one-line fix: introduces make_jobs variable that emits -j{nproc} for a positive job count or -j (unlimited) when nproc is 0, eliminating the invalid make -j 0 invocation.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[build_nccl_ep_submodule] --> B[get_max_jobs_for_parallel_build]
    B --> C{NVTE_BUILD_MAX_JOBS\nor MAX_JOBS\nor --parallel=N set?}
    C -- Yes --> D[nproc = N]
    C -- No --> E[nproc = 0]
    D --> F{nproc truthy?}
    E --> F
    F -- Yes, nproc > 0 --> G[make_jobs = '-jN']
    F -- No, nproc == 0 --> H[make_jobs = '-j' unlimited]
    G --> I["make -jN -C nccl_ep lib"]
    H --> J["make -j -C nccl_ep lib"]

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_{Reviews (2): Last reviewed commit: "Merge branch 'main' into ep_jax" | Re-trigger Greptile}