Is it possible to force the A64 to boot in FEL mode, and if yes, how ?
(I would like to flash the eMMC without using a SD card)
You've read https://linux-sunxi.org about FEL mode?
Including but not only https://linux-sunxi.org/A64
Yes, I have,
I understand that it goes to FEL when no other media is found.
I wish I had a button or a jumper to force it, namely,
imagine that I am in the process of developing a flash procedure;
(that is what I am currently doing ...)
I have to remove the SD card and disable the eMMC boot each time
to achieve it, that it not really convenient.