As source code shows , many files have single and multi two different version , i.e. yaffs_mtdif2_multi.c and yaffs_mtdif2_single.c , yportenv_multi.h and yportenv_single.h. there functions look same. So what¡¯s the real different of the two different? And if don¡¯t use yaffs with OS,and I could comment these files? Wish anyone¡¯s help. ---------- Regards, Ezio