Disable Hopper GLM shared-expert fusion for modelopt_fp4 Marlin (#37325)

python/sglang/srt/models/deepseek_v2.py

@@ -200,6 +200,7 @@ from sglang.srt.utils import (
     LazyValue,
     add_prefix,
     is_non_idle_and_non_empty,
+    is_sm90_supported,
     make_layers,
     use_intel_amx_backend,
 )
@@ -2973,6 +2974,17 @@ class DeepseekV2ForCausalLM(nn.Module, DeepseekV2WeightLoaderMixin):
             )
         if get_exec().moe.enforce_shared_experts_fusion:
             return None
+        if (
+            quant_config is not None
+            and quant_config.get_name() == "modelopt_fp4"
+            and is_sm90_supported()
+            and get_moe_runner_backend().is_marlin()
+        ):
+            return (
+                "Hopper modelopt_fp4 with moe_runner_backend=marlin: "
+                "fusion off by default until the shared-expert fused load path "
+                "is validated."
+            )
         if is_sbo_enabled() or is_tbo_enabled():
             return "SBO/TBO enabled: incompatible with fusing shared expert into MoE kernel."
         if is_deepep_class_backend():