[XPU][Fix] Pack device-pointer tables as uint64 to avoid 64-bit address overflow (#35051)

Co-authored-by: roopaksrivastav <roopak.srivastava@intel.com>
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

test/registered/layers/mamba/test_mamba2_mixer.py

@@ -10,14 +10,16 @@ from sglang.srt.distributed.device_communicators.custom_all_reduce_utils import
     update_environment_variables,
 )
 from sglang.srt.distributed.parallel_state import (
+    get_default_distributed_backend,
     init_distributed_environment,
     initialize_model_parallel,
 )
 from sglang.srt.runtime_context import get_parallel
 from sglang.srt.utils import get_device, get_device_count
-from sglang.test.ci.ci_register import register_cuda_ci
+from sglang.test.ci.ci_register import register_cuda_ci, register_xpu_ci
 
 register_cuda_ci(est_time=30, stage="base-b", runner_config="2-gpu-large")
+register_xpu_ci(est_time=60, suite="nightly-xpu-2-gpu", nightly=True)
 
 NUM_GPUS = 2
 
@@ -96,9 +98,12 @@ def mixer2_gated_norm_tensor_parallel(
         }
     )
 
-    # initialize distributed
+    # nccl on CUDA, xccl on XPU, ...; the parameter default is always "nccl".
     init_distributed_environment(
-        world_size=world_size, rank=local_rank, local_rank=local_rank
+        world_size=world_size,
+        rank=local_rank,
+        local_rank=local_rank,
+        backend=get_default_distributed_backend(device.type),
     )
     initialize_model_parallel(tensor_model_parallel_size=world_size)