D407 - A presented firmware places exports at base plus measured offset

Status: decided Date: 2026-08-30

When a run presents a firmware, the firmware region places each library export this project has a measured offset for at a fixed base address plus that offset, and the guest's initial resolver handle is the address of one specific, always-present export placed the same way; a run presenting no firmware keeps the existing resolver-based handoff unchanged.

Why: An open-toolchain guest's own startup code computes its library base from one known export's address and then reaches every other export at base-plus-offset, which is a scheme this project can only satisfy by actually placing thunks at those computed addresses. Because those offsets can sit close together, a placed thunk must fit the real spacing or it overwrites its neighbor.

Rejected:

• Keeping the resolver-only handoff for every run: correct for a guest that resolves by name, and unusable for one that computes a base and offsets instead.