Hi all The question is regarding thumb mode. we have observed few points, 1. In Some cases size of .o file increase in thumb mode. when i dissamble it i found all instruction are 16 bit.In what cases size increases? 2. How much size will be reduce as compared with ARM mode.? 3. Code reduction depends on what ? 4. How much performance effect with Arm and Thumb mode. 5. we also observed that size of binary increase in some cases,we have check with open source code iozone. if you compile then iozone file size reduce with thumb mode whereas other binary fileop increase. Best Regards Naveen