goosnarrggh

I'm afraid I have taken it as far as I can with the equipment I have: My own hardware is now working fine, and whatever problems other people are having must be due to a different root cause. Since I am not having that problem (whatever it is), there's no way for me to even begin to try to fix it. @Super8film do you have a USB-TTL serial cable? If so, then maybe you could hook it up (serial terminal settings for this board are 8N1-57600 bps) and try to capture a verbose log of what the bootloader and kernel init process have to say while the board is booting? That might provide some evidence that could be used to try to solve your problem too.

I've been trying to bring up Armbian on my Banana Pi M2 Ultra (with A40i SoC). First I tried using the community rolling release, and then building it myself from source code. In every case, it was failing to boot; on the HDMI console it was hanging at the stage where the initrd was attempting to scan for the root partition. ("Scanning for btrfs filesystems") Taking a closer look at the verbose output of the UART console during a boot attempt, I saw that there was an error message about the sunxi-mmc device driver experiencing a failure while it was enumerating the EMMC chip: [ 4.136553] mmcblk2: mmc2:0001 8GTF4R 7.28 GiB [ 4.144362] sunxi-mmc 1c11000.mmc: data error, sending stop command [ 4.150727] sunxi-mmc 1c11000.mmc: send stop command failed On a hunch, I patched the device tree to disable that interface. After compiling that change and installing a new image on a microSD card, the board booted flawlessly, and I am now in a working desktop environment. This leads me to a question: How likely is it that there's just some damaged/defect on my particular board which makes its EMMC unusable? (In which case I might stop here, and be satisfied with the result: Because, I'm not particularly interested in working with the EMMC chip anyway.) Or, it is possible that there's a systemic problem with the Banana Pi M2 Ultra device tree which would be equally impacting everyone's ability to boot? (In which case it might be worthwhile to dig a little deeper, try to figure out why the kernel is hanging when it attempts to enumerate the EMMC chip, and perhaps submit a patch to fix the problem.) Has anyone else experienced this? Or, in case this is a systemic problem, does anyone have some advice about the most appropriate next steps to contribute a fix back to the community?