JdeBPIt's an idea that superficially sounds good, but in practice it has a whole shedload of implementation problems that make it unfeasible as it stands. A précis of just a few:
1. Drivers for writable persistent storage might not have been loaded yet.
2. Your driver might be part of the writable persistent storage stack.
3. You really don't want to be writing to a corrupted filesystem before AUTOCHK.
4. File access has to be at PASSIVE_LEVEL.