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name: ops-and-builds description: "Choose MMCV package variants, inspect compiled ops availability, and troubleshoot install, build, CUDA, and backend failures." disable-model-invocation: true metadata: disco-role: operating license: Apache 2.0

MMCV Ops And Builds

Use this sub-skill when a task involves installing MMCV, deciding between mmcv and mmcv-lite, checking whether compiled mmcv.ops are available, selecting a wheel or source build, or diagnosing native-extension/CUDA/backend errors.

Route Here

• The user needs NMS, ROI/rotated ROI pooling, deformable convolution, sparse convolution, 3D/point-cloud ops, attention kernels, focal losses, or other mmcv.ops APIs.
• The user reports No module named mmcv.ops, No module named mmcv._ext, shared-object load errors, undefined symbols, CUDA kernel errors, or build failures.
• The user asks which package to install for CPU-only, CUDA, MLU, MUSA, NPU, MPS, or lite/no-ops workflows.
• The user needs verification commands after installing or building MMCV.

Route Elsewhere

• Pure image/video/visualization utilities belong in ../media-processing/.
• Data transform pipelines belong in ../data-transforms/.
• CNN layer builders that do not require compiled mmcv.ops belong in ../cnn-model-building/.

Start With Package Selection

1. Use mmcv-lite when the workflow does not import mmcv.ops and does not need compiled native kernels.
2. Use full mmcv when any compiled op is required; in MMCV 2.x, mmcv is the full package and mmcv-lite is the lite package.
3. Do not install both packages in one environment. If switching variants, uninstall the other variant first.
4. Treat compiled ops as conditional: successful import mmcv does not prove that mmcv.ops or mmcv._ext exists.

Key References

• Read references/install-and-build.md for package choice, MIM/pip/source-build flows, environment variables, compatibility checks, and verification commands.
• Read references/ops-reference.md for ops families, representative APIs, and backend support cautions.
• Read references/troubleshooting.md for symptom-to-cause recovery guidance.
• Run scripts/check_mmcv_install.py to inspect installed package facts without relying on the original checkout.

Diagnostic Commands

python scripts/check_mmcv_install.py
python scripts/check_mmcv_install.py --require-ops
python scripts/check_mmcv_install.py --require-cuda --require-ops

The checker reports import/package/Torch/CUDA facts, handles missing ops gracefully, and exits nonzero only when a required check fails.