Look at developing for MSP430s with FRAM -- these microcontrollers have a decent amount of FRAM with full persistence, full XIP etc, up to 256 kB; but only 8 kB

Look at developing for MSP430s with FRAM -- these microcontrollers have a decent amount of FRAM with full persistence, full XIP etc, up to 256 kB; but only 8 kB or less of traditional SRAM. Even in this world, where you /could/ have everything persisted, you still end up aware of the persistence boundary and using SRAM both for the absolutely highest-performance code (e.g. interrupt handlers; FRAM has more wait states than SRAM in this implementation), but more interestingly for things that specifically /should not/ be persisted (e.g. the bytes storing whether your POST has completed, hardware initialized, etc). You can come close to persistence-oblivious, especially at a conceptual "application layer", but the overall implementation still ends up persistence-aware.