[CUDA] Add note about selecting multiple GPUs to docs
@@ -44,7 +44,9 @@ Building pocl with CUDA support
4) Configuration
~~~~~~~~~~~~~~~~
- Use ``POCL_DEVICES=CUDA`` to select only CUDA devices.
+ Use ``POCL_DEVICES=CUDA`` to select only CUDA devices. If the system has more
+ than one GPU, specify the ``CUDA`` device multiple times (e.g.
+ ``POCL_DEVICES=CUDA,CUDA`` for two GPUs).
The CUDA backend currently has a runtime dependency on the CUDA toolkit. If
you receive errors regarding a failure to load ``libdevice``, you may need
