This presentation describes the revised TF-RMM Low-VA MMU and global-runtime-data design required to support Live Firmware Activation (LFA). Compared to the earlier approach (outlined in the TFA Tech Forum session on 12-Jun-2025 [1] ), which assumed mostly fixed boot time mappings and per-platform handcrafted Low-VA contexts, the new design is driven by several changes in RMM specification: RMM must now support runtime mapping/unmapping of PAs for RMM objects like struct granule , reuse those dynamic mappings across LFA transitions. These PAs can come either from NS world at runtime or EL3 reservation from RMM carveout.

In order to migrate Stage 1 dynamic mappings across LFA instances, RMM needs to reduce dependence on platform-specific MMU setup, and provide a structured framework for allocating, versioning and migrating global runtime data. The Stage 1 Low-VA is therefore split into static and dynamic regions managed by the common xlat layer. The detailed design is captured in the TF-RMM wiki RFC “TF-RMM Live Firmware Activation [2]” and builds on the initial design presented in the TFA Tech Forum session on 12-Jun-2025 [1] :