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[Spark bug] Fix arch 12.1 -> "sm120a" flag for Spark, CUDA 12.9 #2839

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Merged
aleozlx merged 2 commits into from
Mar 21, 2026
Merged

[Spark bug] Fix arch 12.1 -> "sm120a" flag for Spark, CUDA 12.9 #2839

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fb30b7d
fix 120a flag for spark on cuda 12.9
kahyunnam Mar 20, 2026
4c38cbd
fix 120a flag for spark on cuda 12.9
kahyunnam Mar 20, 2026
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22 changes: 7 additions & 15 deletions flashinfer/compilation_context.py
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Original file line number Diff line number Diff line change
Expand Up @@ -36,28 +36,20 @@ def _normalize_cuda_arch(major: int, minor: int) -> tuple[int, str]:
tuple with the correct architecture suffix for nvcc.

SM 9.x -> 'a' suffix (e.g. compute_90a)
SM 12.x -> always normalized to SM 120 with 'f' suffix (e.g. compute_120f)
when the installed CUDA toolchain supports it (CUDA >= 13.0),
otherwise 'a'. This covers both SM 12.0 and SM 12.1 (DGX Spark).
SM 12.x -> always normalized to SM 120 with 'f' suffix (e.g. compute_120f).
This covers both SM 12.0 and SM 12.1 (DGX Spark) when the installed CUDA toolchain supports it (CUDA >= 12.9).
SM 10+ -> 'a' suffix (e.g. compute_100a)
SM < 9 -> no suffix
"""
if major == 9:
return (major, str(minor) + "a")
elif major == 12:
try:
from flashinfer.jit.cpp_ext import is_cuda_version_at_least
from flashinfer.jit.cpp_ext import is_cuda_version_at_least

if is_cuda_version_at_least("13.0"):
return (major, "0f")
except (ImportError, RuntimeError, ValueError):
logger.debug(
"Could not determine CUDA version; "
"falling back to 'a' suffix for SM %d.%d",
major,
minor,
)
return (major, "0a")
if is_cuda_version_at_least("12.9"):
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kahyunnam marked this conversation as resolved.
return (major, "0f")
else:
raise RuntimeError("SM 12.x requires CUDA >= 12.9")
elif major >= 10:
return (major, str(minor) + "a")
return (major, str(minor))
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