Take a look at MCU API | Intel® Developer Zone . Here you’ll find some functions of the MCU API.
You can also take a look at the directory C:\...\edison-mcusdk-win64-1.0.10\docs\api_doc\html\mcu__api_8h . Here you’ll find a detailed description of of the Edison MCU API.
Thanks Sergio (@Intel_Alvarado) for the response.
I have looked at MCU API, but couldn't find anything related to flash operation. In my case, I want to save raw data at about 1.5KB/s into a file. Is it possible to write to a file in the flash while the host CPU sleeps? The MCU subsystem picture shows "shared memory" between the MCU and the host CPU. But couldn't find anything related to MCU writing to eMMC.