disable default MKLDNN for cross compilation (apache#13893)

* disable default MKLDNN for cross compilation

* adding temporary debug logs

CMakeLists.txt

@@ -1,7 +1,17 @@
 cmake_minimum_required(VERSION 3.0.2)
 
+# workaround to store CMAKE_CROSSCOMPILING because is getting reset by the project command
+if(CMAKE_CROSSCOMPILING)
+  set(__CMAKE_CROSSCOMPILING ${CMAKE_CROSSCOMPILING})
+  set(__CMAKE_CROSSCOMPILING_OVERRIDE ON)
+endif()
+
 project(mxnet C CXX)
 
+if(__CMAKE_CROSSCOMPILING_OVERRIDE)
+  set(CMAKE_CROSSCOMPILING ${__CMAKE_CROSSCOMPILING})
+endif()
+
 if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/build/private/local_config.cmake)
   include(${CMAKE_CURRENT_SOURCE_DIR}/build/private/local_config.cmake)
 endif()
@@ -20,7 +30,7 @@ mxnet_option(USE_F16C             "Build with x86 F16C instruction support" ON)
 mxnet_option(USE_LAPACK           "Build with lapack support" ON)
 mxnet_option(USE_MKL_IF_AVAILABLE "Use MKL if found" ON)
 mxnet_option(USE_MKLML_MKL        "Use MKLDNN variant of MKL (if MKL found)" ON IF USE_MKL_IF_AVAILABLE AND (NOT APPLE))
-mxnet_option(USE_MKLDNN           "Use MKLDNN variant of MKL (if MKL found)" ON IF USE_MKL_IF_AVAILABLE AND (NOT APPLE) AND (NOT MSVC) AND (CMAKE_SYSTEM_PROCESSOR MATCHES x86_64))
+mxnet_option(USE_MKLDNN           "Use MKLDNN variant of MKL (if MKL found)" ON IF USE_MKL_IF_AVAILABLE AND (NOT APPLE) AND (NOT MSVC) AND (CMAKE_HOST_SYSTEM_PROCESSOR STREQUAL "x86_64") AND (NOT CMAKE_CROSSCOMPILING))
 mxnet_option(USE_OPERATOR_TUNING  "Enable auto-tuning of operators" ON IF NOT MSVC)
 mxnet_option(USE_GPERFTOOLS       "Build with GPerfTools support (if found)" ON)
 mxnet_option(USE_JEMALLOC         "Build with Jemalloc support"   ON)
@@ -41,6 +51,10 @@ mxnet_option(USE_TENSORRT         "Enable infeference optimization with TensorRT
 mxnet_option(USE_ASAN             "Enable Clang/GCC ASAN sanitizers." OFF)
 mxnet_option(ENABLE_TESTCOVERAGE  "Enable compilation with test coverage metric output" OFF)
 
+message(STATUS "CMAKE_CROSSCOMPILING ${CMAKE_CROSSCOMPILING}")
+message(STATUS "CMAKE_HOST_SYSTEM_PROCESSOR ${CMAKE_HOST_SYSTEM_PROCESSOR}")
+message(STATUS "CMAKE_SYSTEM_PROCESSOR ${CMAKE_SYSTEM_PROCESSOR}")
+
 message(STATUS "CMAKE_SYSTEM_NAME ${CMAKE_SYSTEM_NAME}")
 if(USE_CUDA AND NOT USE_OLDCMAKECUDA)
   message(STATUS "CMake version '${CMAKE_VERSION}' using generator '${CMAKE_GENERATOR}'")