====== EVE-K OS: Check Version and Boot from IMGB Partition ======

===== Overview =====

EVE-OS uses an A/B partition scheme with two copies of the root filesystem:
  * **IMGA** — partition 2 (primary)
  * **IMGB** — partition 3 (fallback / alternate)

The active partition is selected at boot via GPT attribute flags read by GRUB.

----

===== Check Which Partition is Currently Active =====

<code bash>
cat /run/eve.id
</code>

This returns either ''IMGA'' or ''IMGB''.

----

===== Check the EVE Version on Each Partition =====

==== Currently Running Partition ====

<code bash>
cat /etc/eve-release
</code>

==== Inactive Partition (IMGB) ====

<code bash>
# Mount IMGB
mkdir -p /tmp/imgb
mount -t squashfs /dev/sda3 /tmp/imgb

# Read the version
cat /tmp/imgb/etc/eve-release

# Unmount when done
umount /tmp/imgb
</code>

> **Note:** If your disk is not ''/dev/sda'' (e.g. NVMe), adjust accordingly.\\ 
> For NVMe drives use ''/dev/nvme0n1p3'' instead of ''/dev/sda3''.

----

===== Partition Layout Reference =====

^ Number ^ Name   ^ Size   ^ Description                        ^
| 1      | EFI    | 2.0 GiB | EFI System partition (bootloader)  |
| 2      | IMGA   | 4.0 GiB | Primary EVE-OS root filesystem     |
| 3      | IMGB   | 4.0 GiB | Alternate EVE-OS root filesystem   |
| 4      | CONFIG | 5.0 MiB | Edge node identity & configuration |
| 9      | P3     | ~467 GiB | Persistent data (read-write)      |

To verify on your device:

<code bash>
sgdisk -p /dev/sda
</code>

----

===== Revert Boot to IMGB Partition =====

==== Step 1 — Clear Priority Flag from IMGA ====

<code bash>
sgdisk --attributes=2:clear:48 /dev/sda
</code>

==== Step 2 — Set Priority and Successful Flags on IMGB ====

<code bash>
sgdisk --attributes=3:set:48 /dev/sda
sgdisk --attributes=3:set:56 /dev/sda
</code>

^ Bit ^ Meaning                          ^
| 48  | Priority — GRUB prefers this partition |
| 56  | Successful — partition is bootable     |

==== Step 3 — Reboot ====

<code bash>
reboot
</code>

==== Step 4 — Verify After Reboot ====

<code bash>
cat /run/eve.id      # should now show IMGB
cat /etc/eve-release # confirm the version
</code>

----

===== To Revert Back to IMGA =====

<code bash>
sgdisk --attributes=3:clear:48 /dev/sda
sgdisk --attributes=2:set:48 /dev/sda
sgdisk --attributes=2:set:56 /dev/sda
reboot
</code>

----

===== Notes =====

  * IMGA and IMGB are **read-only** squashfs filesystems — they cannot be modified while running.
  * The CONFIG and EFI partitions must be preserved — corrupting them requires a full reinstall.
  * These changes take effect on the **next reboot** only.
  * After an OTA update, EVE normally switches partitions automatically. This procedure is for **manual intervention** only.