issue with eMMC

[cowboyai]

I have eMMC Booting, as in it boots and starts Stage 1, but fails to mount /dev/disk/by-partlabel/disk-sysboot-root
when targetting /dev/mmcblk0

if I target /dev/sda and put it on a usb, it works fine and boots correctly.

I have verified I am booting the correct device because I pull out the usb and it has to be booting from emmc.
I am deploying via nixos-anywhere with a disko configuration.

Here is my config:

{
  # This file is ONLY the system drive
  # NAS Settings are in disko-nas.nix

  # eMMC boots here, not the boot0/1 partitions, but we do need initial mbr offset for it to boot correctly, otherwise /boot doesn't mount either
   disko.devices = {
    disk = {
      # the bootable drive...
      sysboot = {
        # this is the emmc device
        device = "/dev/mmcblk0";
        type = "disk";
        content = {
          type = "gpt";
          partitions = {
            MBR = {
              type = "EF02"; # for MBR
              size = "1M";
              priority = 1; # Needs to be first partition
            };
            ESP = {
              type = "EF00";
              size = "500M";
              content = {
                type = "filesystem";
                format = "vfat";
                mountOptions = [ "umask=0077" ]; # make it NOT world readable
                mountpoint = "/boot";
              };
            };

            root = {
              size = "100%";
              content = {
                type = "filesystem";
                format = "ext4";
                mountpoint = "/";
              };
            };
          };
        };
      };
    };
  };
}

full configs are available at: https://github.com/TheCowboyAI/nixos-flashstor

Am I not setting something correctly for eMMC? as I understand, getting the offset right to initiate boot was the only difference.

[iFreilicht]

What's the error message?

[cowboyai]

waiting for device /dev/disk/by-partlabel/disk-sysboot-root to appear.........
Timed out waiting for device /dev/disk/by-partlabel/disk-sysboot-root
trying anyway....
mounting /dev/disk/by-partlabel/disk-sysboot-root on / ...
/dev/disk/by-partlabel/disk-sysboot-root: can't lookup block device

[cowboyai]

is this helpful?

from writing to the eMMC with nixos-anywhere output:

/dev/mmcblk0: 8 bytes were erased at offset 0x00000200 (gpt): 45 46 49 20 50 41 52 54
/dev/mmcblk0: 8 bytes were erased at offset 0x1d1fffe00 (gpt): 45 46 49 20 50 41 52 54
/dev/mmcblk0: 2 bytes were erased at offset 0x000001fe (PMBR): 55 aa
+ dd if=/dev/zero of=/dev/mmcblk0 bs=440 count=1
Scudo ERROR: invalid alignment requested in aligned_alloc: 4096, alignment must be a power of two and the requested size 0x1b8 must be a multiple of alignment
++ realpath /dev/nvme0n1
+ disk=/dev/nvme0n1
+ lsblk -a -f

[cowboyai]

full log, these are the only errors I see are alignment errors
deploy-emmc-20241022-152917.txt

[iFreilicht]

So the installation logs look good. These alignment errors are a little suspicious, not sure where the weird blocksize of 440 bytes is coming from, but probably not the root of the issue.

I'm also suspicious of the size of the MBR partition, maybe the small size causes the alignment issues?

Does Linux offer you to enter a rescue prompt after failing to boot? If so, can you enter it and check the presence of the eMMC device and its by-partlabel symlinks?

I'm also wondering if you maybe have to add additional drivers at boot for eMMC.