How does SW4 affect on booting?


(michal5520pl) #1

Hello, What influence has SW4 on booting? Thank you, Michał.


(Андрей Панов) #2

I’ve found, that:

  • if it is off (0), board boots from EMMC
  • if it is on (1), board boots from SPI flash, and in this case, whed SD card is inserted, it is detected and SPI loader wants to boot from SD, but card layout is unknown. If SD isn’t inserted, board boots to LittleKernel and LK’s shell is started.

Question for BPI staff – what ls a layout of bootable SD card?


(michal5520pl) #3

My board boots from SD card only in SW4’s position 0


(Андрей Панов) #4

Strange, I’ve seen no difference booting with SW4=0 when SD is inserted or not. It always boots Android from EMMC.

BPI W2 boot with SW4=1 and SD inserted - https://pastebin.com/NT0ECNCf

BPI W2 boot with SW4=0 and SD inserted - https://pastebin.com/8rFNCUX5

BPI W2 boot with SW4=0 and no SD inserted - https://pastebin.com/0MaJEKwT

And I see no way to boot from SD directly


(Ning) #5

please refer to