Runbooks — pick your path#

A runbook doesn’t repeat the how-to. It routes you through the layer components in the right order for one concrete situation, and forwards you from each step to the next. Read the four-layer model once, then pick the path that matches where you’re starting.

flowchart TD
    A[Where are you starting?] --> B{Does the printer boot?}
    B -->|No, or a bad flash to undo| R[Recovery]
    B -->|Yes| C{Replacing the OS?}
    C -->|No, migrate in place| OS1[Over stock firmware]
    C -->|Yes, and I have an eMMC reader| OS2[With an eMMC reader]
    C -->|Yes, but no reader| OS3[Over stock firmware<br/>OS reprovision in place]

• Over stock firmware — the printer works and you migrate in place. The vendor OS stays; the application and MCU firmware move to upstream; the OS is optional at the end.
• With an eMMC reader — clean-slate build from a blank or reflashed eMMC: OS first, application on top, MCUs usually untouched because they survived whatever you’re rebuilding from.
• Recovery — a machine that won’t boot, or a bad flash to roll back.

No reader and you still want a fresh OS? You can reprovision the OS in place — see in place, no eMMC reader — then join the application steps of either runbook.