SM 120 (Blackwell GeForce RTX 50 Series) Block-Scaled MMA Runtime Assertion Failure
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- Dominant language
- C++
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Description
Which component has the problem?
CUTLASS C++
Bug Report
Which component has the problem?
CUTLASS C++
Bug Report
Environment
- GPU: NVIDIA GeForce RTX 5070 Ti (SM 120, Compute Capability 12.0)
- Driver: 581.80 (Windows)
- CUDA Toolkit: 13.0.88
- OS: WSL Ubuntu 22.04 on Windows 11
- CUTLASS: main branch (latest as of Nov 2025)
Issue
All Blackwell GeForce examples (79a-79d) fail at runtime with arch conditional MMA assertion:
Assertion 0 && "ERROR : Arch conditional MMA instruction used without targeting appropriate compute capability. Aborting.\n" failed.
../../include/cutlass/gemm/kernel/sm90_gemm_tma_warpspecialized_cooperative.hpp:366
Contributor guide
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First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reproducing the failure with Blackwell examples 79a–79d on the stated RTX 5070 Ti environment. Read the assertion at include/cutlass/gemm/kernel/sm90_gemm_tma_warpspecialized_cooperative.hpp:366 and inspect how the examples target the compute capability. Done means the affected examples run without the arch-conditional MMA assertion.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- cpp
- Domain
- hpc
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Quiet
- Clarity
- Mostly clear
- Newbie friendliness
- 38/100