diff --git a/nanochat/flash_attention.py b/nanochat/flash_attention.py
index c79d124..67917b1 100644
--- a/nanochat/flash_attention.py
+++ b/nanochat/flash_attention.py
@@ -26,6 +26,8 @@ def _load_flash_attention_3():
     if not torch.cuda.is_available():
         return None
     try:
+        # FA3 kernels are currently compiled for Hopper (sm90) and Ampere (sm80/sm86)
+        # Ada (sm89), Blackwell (sm100) need SDPA fallback until FA3 is recompiled
         from kernels import get_kernel, has_kernel
         supported = has_kernel(hf_kernel)
         if not supported: