@mitu thx...there seems to be some misleading information on the page you linked...and i seem to have picked the wrong info...
0x4 USB-MSD USB mass storage boot - See USB mass storage boot
0xf41 Try SD first, followed by USB-MSD then repeat (default if BOOT_ORDER is empty)
0xf14 Try USB first, followed by SD then repeat
funnily, i had (tried to) changed it from gui...and selected the option: boot from usb, fallback to sdcard...
let me try changing it to 0xf41... i'll report back
edit: I changed it:
and now i don't even see the bootloader screen anymore...instead it directly boots retropie from sdcard
edit2: 0xf14 is the correct mode... problem is not with retropie nor with the config.
I now have tested an usb-stick with recalbox, and it boots just fine... previously i tried to boot lakka 64bit from usb, which did/does not work.
I guess i need to check lakka forum for support...