Currently, we build two wheel variants: xgboost-cpu (which excludes GPU code) and xgboost (where the GPU code targets CUDA 12.4). In #10729, xgboost is found to conflict with another package using CUDA 11.

Following the practices of RAPIDS, we should distribute separate wheels targeting CUDA 11 and CUDA 12.

Proposal. Build four wheel variants.

• xgboost-cpu: excludes the GPU code
• xgboost-cu11: builds GPU code with CUDA 11, depends on nvidia-nccl-cu11.
• xgboost: builds GPU code with CUDA 12, depends on nvidia-nccl-cu12.
• xgboost-cu12: a stub package directing users to install xgboost. Something like https://pypi.org/project/cuml. The stub package can be replaced with a real one when the main package xgboost transitions to CUDA 13.

Prerequisites

• Project Limit Request: XGBoost - 20 GiB pypi/support#4695
• Need to file another issue to increase file size for xgboost-cu11 to 200 MiB.
• Reduce the wheel size by dropping some archs, like sm_50.
• [CI] Use rapids-dependency-file-generator to generate pyproject.toml #10803