[BUILD] use sm_100f when compiling flashmla to fix support on sm103 (vllm-project#30705)

Signed-off-by: Shengqi Chen <harry-chen@outlook.com>

Author: Harry-Chen

cmake/external_projects/flashmla.cmake

@@ -35,16 +35,21 @@ message(STATUS "FlashMLA is available at ${flashmla_SOURCE_DIR}")
 # sm90a
 
 set(SUPPORT_ARCHS)
-if(${CMAKE_CUDA_COMPILER_VERSION} VERSION_GREATER 12.3)
-    list(APPEND SUPPORT_ARCHS 9.0a)
+if(${CMAKE_CUDA_COMPILER_VERSION} VERSION_GREATER_EQUAL 12.3)
+    list(APPEND SUPPORT_ARCHS "9.0a")
 endif()
-if(${CMAKE_CUDA_COMPILER_VERSION} VERSION_GREATER 12.8)
-    list(APPEND SUPPORT_ARCHS 10.0a)
+if(${CMAKE_CUDA_COMPILER_VERSION} VERSION_GREATER_EQUAL 12.9)
+    # CUDA 12.9 has introduced "Family-Specific Architecture Features"
+    # this supports all compute_10x family
+    list(APPEND SUPPORT_ARCHS "10.0f")
+elseif(${CMAKE_CUDA_COMPILER_VERSION} VERSION_GREATER_EQUAL 12.8)
+    list(APPEND SUPPORT_ARCHS "10.0a")
 endif()
 
 
 cuda_archs_loose_intersection(FLASH_MLA_ARCHS "${SUPPORT_ARCHS}" "${CUDA_ARCHS}")
 if(FLASH_MLA_ARCHS)
+    message(STATUS "FlashMLA CUDA architectures: ${FLASH_MLA_ARCHS}")
     set(VLLM_FLASHMLA_GPU_FLAGS ${VLLM_GPU_FLAGS})
     list(APPEND VLLM_FLASHMLA_GPU_FLAGS "--expt-relaxed-constexpr" "--expt-extended-lambda" "--use_fast_math")
 
@@ -126,7 +131,8 @@ if(FLASH_MLA_ARCHS)
         $<$<COMPILE_LANGUAGE:CUDA>:-UPy_LIMITED_API>
         $<$<COMPILE_LANGUAGE:CXX>:-UPy_LIMITED_API>)
 else()
-    # Create empty targets for setup.py when not targeting sm90a systems
+    message(STATUS "FlashMLA will not compile: unsupported CUDA architecture ${CUDA_ARCHS}")
+    # Create empty targets for setup.py on unsupported systems
     add_custom_target(_flashmla_C)
     add_custom_target(_flashmla_extension_C)
 endif()