When I try to update eboot.spl via Update Tool, it shows update failed. The eboot.spl is on FlashDisk. But it works if eboot.spl is from USB stick. Is that a issue?
This behavior is expected:
The update procedure requires that the eMMC flash device is switched to the eMMC Boot Partition. As a consequence, the operating system does not have access to the eMMC User Partition anymore, where the /Flashdisk/ folder is located.
Thanks Andy. So it also means that everything on eMMC Boot Partition including SPL bootloader, eboot, Config block are not supported to be updated from FlashDisk, only from SD card, USB stick out of eMMC User Partition.