Enable native ModelOpt quantization support (2/3) (#9991)

Signed-off-by: Zhiyu Cheng <zhiyuc@nvidia.com>

python/sglang/srt/server_args.py

@@ -178,6 +178,8 @@ class ServerArgs:
     model_loader_extra_config: str = "{}"
     trust_remote_code: bool = False
     modelopt_quant: Optional[Union[str, Dict]] = None
+    modelopt_checkpoint_restore_path: Optional[str] = None
+    modelopt_checkpoint_save_path: Optional[str] = None
     context_length: Optional[int] = None
     is_embedding: bool = False
     enable_multimodal: Optional[bool] = None
@@ -1504,6 +1506,21 @@ class ServerArgs:
             "Supported values: 'fp8', 'int4_awq', 'w4a8_awq', 'nvfp4', 'nvfp4_awq'. "
             "This requires the NVIDIA Model Optimizer library to be installed: pip install nvidia-modelopt",
         )
+        parser.add_argument(
+            "--modelopt-checkpoint-restore-path",
+            type=str,
+            default=ServerArgs.modelopt_checkpoint_restore_path,
+            help="Path to restore a previously saved ModelOpt quantized checkpoint. "
+            "If provided, the quantization process will be skipped and the model "
+            "will be loaded from this checkpoint.",
+        )
+        parser.add_argument(
+            "--modelopt-checkpoint-save-path",
+            type=str,
+            default=ServerArgs.modelopt_checkpoint_save_path,
+            help="Path to save the ModelOpt quantized checkpoint after quantization. "
+            "This allows reusing the quantized model in future runs.",
+        )
         parser.add_argument(
             "--kv-cache-dtype",
             type=str,