Skip to content

Boot flow and application slots

Normal boot path

The internal ROM initializes the platform and loads additional firmware from SPI/NAND. The user-visible flow continues through boot animation, loading application, and menu/system modules before an MBA application entry is called.

An MBA application is entered as a callback inside a live firmware environment. It is not a reset image. The launcher can leave display interrupts, watchdog, resident services, and memory state active.

Supported slot profiles

The builder has deterministic metadata profiles for SY and legacy G1. Each profile fixes:

  • runtime image base and body load address;
  • application entry;
  • protected callback/data ranges;
  • maximum payload capacity and complete file size;
  • launcher role and footer metadata.

Changing only the header entry does not relocate code. Build the payload and container for the same profile.

SY

SY is the canonical new-project profile and normal unified-CLI target. Routine emulator runs overlay the discovered system role in memory. An explicit copied NAND replaces the discovered system application and validates persistent installation through normal boot.

Physical replacement is inherently high risk because a bad system application can prevent normal startup. It requires recovery backups and complete emulator validation.

G1

G1 is retained for legacy compatibility and maintained examples. It is not the default template for a new port. Build it explicitly and install only through the discovered G1 target.

Exit and handoff

A top-level return leaves the current MBA. For asynchronous relaunch, schedule the request, return zero from the frame callback, finalize resident runtime, and return from the entry. A permanent loop or continued nonzero frames can prevent the handoff.

Diagnostic shortcuts

The unified CLI's role-aware transient overlay is the canonical application smoke-test path. A claim about persistent install, slot discovery, or filesystem behavior additionally needs copied-NAND validation because the overlay does not test that storage contract. Forced-PC/handoff shortcuts remain diagnostic only.