nvfp4 support for Spark DGX

[vidavakil]

Hello,

I'm trying to use nvfp4 on DGX Spark. From the errors I get and the issues and PRs (e.g., #2255 and #2279) I understand that I have to build transformer-engine for the right sm_xxxa (NVTE_CUDA_ARCHS=121a ?). But what I have tried has not worked yet.

If/when this feature is supported, could you please share how exactly to build TE with nvfp4 support for DGX Spark and how to properly specify NVFP4BlockScaling() flags? Also, the right NGC to use?