A platform-based emulator for mass-storage flash cards evaluation in embedded systems

In this work we present a simulation environment, built around the QEmu emulator, that allows the evaluation of mass-storage Flash-Card memories, specifically embedded Multimedia Cards (e-MMC). Flash card memories are internally complex systems containing, along with the memory array, an intelligent controller, running its own firmware. The controller is a critical unit, since its functions are not limited in providing a standard interface between the internal memory array and the user, but they are much more elaborate (e.g. buffering, erase sequences, garbage collection, flash memory wear leveling, etc.). It is then clear that the implementation of these functions can have a strong impact on performances. In this scenario, a simulation environment would be a valuable resource in the design flow, since it could allow the exploration of different internal architectures and firmware implementations, the verification and the estimation of performances of new devices during their design. Using QEmu as base environment, we have developed a fast emulator of a complete embedded system platform, containing a behavioral model of next-generation e-MMC devices, parametrized in order to be portable to future generations of e-MMCs. The whole emulator is fast enough to boot a complete Linux kernel and to launch applications, allowing the analysis of e-MMCs behavior on real use cases, based on actual file systems (e.g. ext2, FAT32, NTFS, etc.) and actual applications or benchmarks.