Changing permission of cramfs file system

I mounted the cramfs image in some directory.The files in that dir are showing the timestamp of 1970-01-01.I am having issues in compressing this开发者_StackOverflow file system because of old time stamp.So i want to change the time stamp using touch command but when i am always getting error Read only file system.

I have also tried remounting as read/write filesystem but even after that i am not able to change the permissions.

Could anyone guide me regarding this.

Thanks and Regards, Mayank

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cramfs is a read-only file system perfect for small-system boot ROMs and other read-only programs and data.

~Hallinan, Christopher (2010-10-26). Embedded Linux Primer: A Practical Real-World Approach (2nd Edition) (Kindle Locations 4746-4747). Pearson Education (USA). Kindle Edition.