How to make a read-only ext4 partition not even change a bit?

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http://stackoverflow.com – I have a weird requirement. In Android the system partition, which is in ext4, is mounted as read-only. But some customer think we can make it safer by locking eMMC sectorc at a lower level. This makes problems. Mounting a partition as ro only protects the files. But in kernel mode, file systems must have some meta data to write onto the storage, even though it's read-only. My question is that is it possible to make an ext4 partition work without changing even a bit? (HowTos)