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B12X Linear BackendÂķ

B12X provides optional CUDA kernels for NVIDIA SM120 and SM121 GPUs. Install the dependency with:

uv pip install "vllm[b12x]"

B12X participates in automatic kernel selection after established optimized backends and before emulation. Select it explicitly with:

vllm serve <model> --linear-backend b12x

Supported ConfigurationsÂķ

Backend Supported configurations
Linear Per-tensor FP8, 128x128 block FP8, MXFP8, NVFP4, and MXFP4

Dense W4A16 layers are not handled by B12X and continue to use another compatible backend such as Marlin.