https://forum.armbian.com/topic/13417-emmc-not-recognised-by-u-boot-not-available-once-booted/

https://forum.khadas.com/t/mainline-u-boot-sometimes-fail-with-unable-to-select-a-mode/9570

u-boot radxa zero 2/8GB

=> mmc list

sd@ffe03000: 0

sd@ffe05000: 1

mmc@ffe07000: 2

=> mmc dev 2

unable to select a mode : -5

=> mmc dev 0

Card did not respond to voltage select! : -110

=> mmc dev 2

unable to select a mode : -5

=> mmc dev 1

Card did not respond to voltage select! : -110

The only solution I see at the moment is to set up the U-Boot environment for boards without eMMC, I can't edit the U-Boot sources. You can close this task if you consider it useless. I only use Manjaro Linux as a boot diagnostic tool, it is not a working distribution for me.

Because Manjaro Linux boots on 512M model from the box and doesn't boot on eMMC models from the box (until you erase the bootloader), I assume that the problem is in U-boot.

We are not going to change boot process to match factory added boot loader. If we give clear instructions what user has to do to get things up, job is done. Manjaro Linux works in very random way as its supported by everyone and no-one at the same time. Its mainline code. Sometimes it works, sometimes not.

We don’t need to proceed on this more than this. Its up to you if you want to understand how and why things are made this way. Sometimes its wrong decision, sometimes a bug. I don’t know what it is, without looking into the code.

radxa zero model 512MB does not have eMMC. I wrote about the need to erase the bootloader in the original post. I have a 4 GB model with an erased bootloader and everything loads perfectly on it. Manjaro Linux loading from sd on all radxa zero models (without eMMC and whith eMMC, if erase android bootloader from eMMC ).

I'm trying to dig U-boot, but my knowledge is not enough to quickly solve this issue.