The Research And Realization Of Transplant UBIFS Into UCOS-Ⅱ

Due to the physical characteristics of NAND flash, NAND flash facing garbage collection, wear leveling and bad block handling three major challenges. For the flash file system, erase and write position is stationary, the flash is easy to produce bad blocks. Therefore, it requires specialized procedures to deal with bad blocks, increase the difficulty and cycle of development. Use a dedicated flash file system is the most widely used in embedded system applications a storage strategy, it supports a log structure, and provide power-down protection, wear leveling, crash recovery mechanisms, and garbage collection mechanism, not only to reduce the flash development difficult but also to extend the life of flash.UBIFS mount time, memory usage and I/O speed does not depend on the flash memory size. UBIFS can support hundreds of G of Flash. UBIFS file system directory is stored in the flash, UBIFS mount do not need to scan the entire flash memory data to re-create the file directory and file information, UBIFS support on-the-flight compression, and optional compression. UBIFS supports write-back, write the data will be cached until the need to write to physical flash, greatly reduce the number of scattered residential block, and to improve the I/O efficiency. In addition the UBIFS use log records to reduce the index update frequency. JFFS2file system cache is very small, its store data performance is nearly synchronous operation, did not play a good cache effects. UBIFS in the design and performance than those YAFFS2, JFFS2is more suitable for the MLC NAND FLASH.UBIFS is currently only used in the Linux kernel and the complexity of the hardware environment. Simple hardware conditions such as microcontroller is needed UBIFS application. The μC/OS-Ⅱ’s appear is for such low-end hardware environment and the embedded system, which on enables simple hardware can achieve many of the features of the operating system, such as multi-tasking, real-time, process communication, and other. For many the μC/OS-Ⅱ application areas, is need flash to store data, in particular for update frequently application, is more need optimized file system for flash memory like UBIFS file system.Firstly, in-depth analysis of the principle of μC/OS-Ⅱ system, analysis of the physical characteristics of NAND flash and the facing challenges, the optimized mainstream file system for NAND flash. Then propose a feasible way to transplant the UBIFS to μC/OS-Ⅱ. Design test program to test the portable code in the final.