Explain to me like i'm 5yo

I have four taters that I somehow got Ubuntu 22.04 DT loaded to and they boot fine. Not so good running like Arduino. Uses up memory and locks up. So I downloaded and loaded Armbian to a SanDisk, removed the eMMC and so far so good running Armbian from the SanDisk. It does a much better job on a 2gb SBC running Arduino.

I don’t have to but I would like to change the eMMC drives to Armbian. The boot order seems to be an issue.
To recap:
Armbian on 128GB SD. Boots and runs fine.
32GB eMMC has Ubuntu 22.04. Disconnected but would like to use.
I want to change the eMMC boot to Armbian. How to and what do we mean by “flash?”

I remember doing this to a blank eMMC but now it always boots to Ubuntu 22.04 and says it’s busy if I try to use DiskImageWriter.

  1. What is DT?
  2. Please write coherently with each individual issue. Your problem description is convoluted.
  3. For help with Armbian, please use their forums. They have a different process for eMMC than our images.
  4. Whatever is on eMMC will boot before MicroSD. This is noted in the boot behavior doc.

desktop almost like cli, command line interface.

I have one issue! I want to overlay Libre’s Ubuntu on the eMMC with an Armbian image that is running well for me. The third line of the recap is pretty clear. Is there a way to change the eMMC?

I had to remove the eMMC so it would boot from the SD card. I’m not really sure I care about this for my application, which is coding sketches for Arduino, but the curiousity is nagging!

Another thought - is there a way to format an eMMC back to knowing nothing so it will be ignored at boot then can be flashed to a new system?

Our images use GRUB and works with GRUB’s os-prober. Armbian does something proprietary and does not work like normal so if you want to dual boot, you have to manually select the boot device in u-boot’s command line. This is rather sophisticated so you have to learn how to use bootcmd on the u-boot console.

If you want to erase eMMC on our images, just run sudo dd if=/dev/zero of=/dev/mmcblk0 bs=1M count=1. This is different if your current OS is Armbian.

Help this old man. Could I boot from eMMC giving me Ubuntu(your build), Open a terminal, dd to my hearts content on the eMMC, effectively blanking the eMMC and system and then boot from the Armbian SD and then flash an image file on usb to the eMMC?

Warning Will Robinson, Warning! Yes you can and I did! dd is not polite and could cause some big bad problems!

I did what I asked above, it did not say in use and cleared it out right now! The eMMC is now ready for a new image. Now I will flash an Armbian image to the eMMC.

Thanks for your help.

You can only have one image on the eMMC. You can do custom partition with multiple OS support but that is for Linux intermediates and above.

For those playing along at home… I did the dd clearing of the eMMC ( sudo dd if=/dev/zero of=/dev/mmcblk0 bs=1M count=1). Then booted Armbian from an SD. Opened a terminal and ran sudo armbian-config. The config listed the blank eMMC as a target. I chose that and it installed itself to the eMMC. It now is bootable from the eMMC.

Armbian has a nice utility to transfer a running image from SD to eMMC. It is called nand-sata-install. As far as I know, it is Armbian-specific. Since I am going the other way (moving away from Armbian to try Libre Computer’s build of Ubuntu 22.04 desktop, I am hoping a similar tool exists since the eMMC cards I purchased from LoveRPi did not come with an adapter to allow me to interface with them as a microSD card. Best of luck to you with Armbian!

eMMC shows up as /dev/mmcblk0 where as MicroSD shows up as /dev/mmcblk1. You can just dd to the file.