Banana Pi M5 Armbian emmc mmcblk1 instead of mmcblk0

[Mechano]

On my Banana Pi M5 Armbian Jammy has a strange device name assignment.

BPi-M5 has internal 16GB eMMC normally named mmcblk0 and microSD named mmcblk1.

Normally it boots from SD and if you install an OS like Raspberry OS for BPi into eMMC, you're still able to boot from SD another OS because RaspiOS maps device correctly.

 

But when Armbian (i.e. Jammy) is installed into eMMC it changes eMMC device to mmcblk1 and SD to mmcblk0, and It prevents SD to boot. 
And if the eMMC OS corrupts and doesn't boot the SBC bricks and TTL connection is needed to erase boot record. 

 

To change OS it's necessary a command to delete boot record and SD on mmblk1 will boot again:
 

dd if=/dev/zero of=/dev/mmcblk1 bs=512 count=1

 

But the OS on eMMC has to boot and be in good working conditions.

 

Also another guy with Orange Pi has noticd this behaviour:

https://forum.armbian.com/topic/9987-sd-card-not-booting-but-works-on-another-emmc-boot-up/

 

It's important to change this behaviour and do it like RaspiOS.

 

[Mechano]

I've discovered more about this beaviour... 
If you have Ubuntu Jammy on eMMC and want to boot another OS from microSD it has to be another Ubuntu with mmcblk1 root disk set somewhere, that overrides the boot priority. 

If you try to boot a RaspiOS for Banana it has set mmcblk0 and will not boot.