yocto-poky/meta/recipes-devtools/cmake/cmake/OEToolchainConfig.cmake

set( CMAKE_SYSTEM_NAME Linux )
set( CMAKE_C_FLAGS $ENV{CFLAGS} CACHE STRING "" FORCE )
set( CMAKE_CXX_FLAGS $ENV{CXXFLAGS}  CACHE STRING "" FORCE )
set( CMAKE ASM_FLAGS ${CMAKE_C_FLAGS} CACHE STRING "" FORCE )
set( CMAKE_LDFLAGS_FLAGS ${CMAKE_CXX_FLAGS} CACHE STRING "" FORCE )
set( CMAKE_FIND_ROOT_PATH $ENV{OECORE_TARGET_SYSROOT} $ENV{OECORE_NATIVE_SYSROOT} )
set( CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER )
set( CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY )
set( CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY )

string(REGEX MATCH "sysroots/([a-zA-Z0-9]+)" CMAKE_SYSTEM_PROCESSOR $ENV{SDKTARGETSYSROOT})
string(REGEX REPLACE "sysroots/" "" CMAKE_SYSTEM_PROCESSOR ${CMAKE_SYSTEM_PROCESSOR})

# Include the toolchain configuration subscripts
file( GLOB toolchain_config_files "${CMAKE_TOOLCHAIN_FILE}.d/*.cmake" )
foreach(config ${toolchain_config_files})
    include(${config})
endforeach()