Erase eMMC and start over? Or boot from SD Card?

Software
1

Hello. I have a working OS installed on my eMMC. I am trying to erase it, and start over so I can boot from the SD card again.

If I remove the eMMC module the board won’t boot at all.

I can’t seem to get it to boot from the SD card… if I could do that I could “dd” the eMMC again.

I think I remember changing some option to force the eMMC as the main boot device but I can’t remember what I did.

2

Are you using a 4K display by chance? Currently there’s a bug in our u-boot that crashes with 4K displays. It’s in the process of getting fixed.

3

ROC-RK3328-CC
32gb eMMC

I am using a 1080p monitor but mostly I don’t use a monitor.
I am running Debian 11 bullseye, booting from the eMMC module.
This works great. Much better than the SD card!

I would like to change the role of the computer and install a different OS.

I can’t boot from SD card… How do I delete the eMMC, erase Debian 11, and boot from the SD card so I can start over and install a new OS on the eMMC?

4

Are you sure you’re flashing the right image correctly on the MicroSD card? Without the eMMC module, it will boot the MicroSD card. To delete the eMMC bootloader, simply run:

sudo dd if=/dev/zero of=/dev/mmcblk0 bs=512 skip=1 count=2047
5

I was doing it wrong. Thanks for the help!

6

I fixed the SD card and I can now boot from the SD card but if I have the eMMC connected it automatically boots from the eMMC card, not the SD card. Is there a way to swap the boot order? Or do I need to hot plug the eMMC after booting from the SD card?

7

Boards have a fixed search order for the bootloader. Once it has found the bootloader on the eMMC, it will boot from it. You can set the operating system boot order via creating a boot.ini file with the necessary boot_targets order saved on the device that the board is booting from.

boot_targets=mmc1 mmc0
9

This is what worked for me:
I had to use terminal or command line for this.
Open a terminal and change directory to boot/efi.
“cd /boot/efi”
Start nano as admin to create the file.
“sudo nano boot.ini”
add your boot targets.
“boot_targets=mmc1 mmc0”
Save the file, exit nano, and reboot.

10

The file needs to be on the first FAT/EFI partition. So mounting points may vary but it’s generally /boot/efi.

11

I corrected “etc” to “efi”. I left that post for anyone that might read it later, it might help them figure it out. Thank you for the correction!

12

echo "boot_targets=usb mmc1 mmc0" > /boot/efi/boot.ini

Until it is included in every image, must need to be done after every image writing.