BPI-M64 eMMC flash
BPI-M64 have support 8G eMMC flash on board by defaults.
also can support 4-64G eMMC for option:
test 64G eMMC flash on BPI-M3, same way can rework on BPI-M64
So, you can burn your image to eMMC flash and boot from eMMC flash.
How to burn Android image to eMMC
please read this book：
2.2.1 How to burn android image to eMMC
How to burn Linux image to eMMC
please read this book:
2.3.1 How to burn linux image to eMMC
the first boot is from microSD card. if you want to boot from eMMC flash ,please remove microSD card from BPI-M64 microSD card slots.