The ctypes-based probing loaded a second libcudart copy into the process,
which corrupted CUDA/runtime state and segfaulted the scheduler processes
shortly after registration (reproducible on prefill ranks, intermittent on
decode). cuda.bindings.runtime.cudaPointerGetAttributes is a properly
typed binding and boots cleanly on both roles.
IntraNodeNvlinkTransport can only register/reach device memory. sglang's
register list includes host regions (aux buffers, some state components);
one host region failed the whole registerLocalMemoryBatch and the engine
rolled back every region, leaving the segment descriptor empty so all KV
transfers failed with 'Requested address ... not found'.
When the intra-node NVLink transport is active (MC_INTRANODE_NVLINK etc.):
- register only device-memory regions (probe via cudaPointerGetAttributes)
- route transfer blocks whose local source is host memory over the ordered
per-endpoint zmq channel (new STATE_DATA message) instead of the engine;
the receiver validates and writes the block into its buffer, relying on
the same ordering guarantee as the aux TCP path
- force aux over the TCP socket path automatically
minke.yu