Correct Method to Access Backend Page Data via PPA

[jjaehoonn]

I am currently implementing a system that performs external backups of the physical page corresponding to a specific LBA whenever a modification request occurs. For testing purposes, I issue write operations using dd, and I have successfully implemented the logic to output the LBA, OLD_PPA, and NEW_PPA during each write event.

However, when I attempt to access the data stored at the corresponding PPA for snapshot generation, the program terminates due to what appears to be a memory access fault. I suspect that my current approach to referencing backend memory may be incorrect or that I am accessing the offset outside of FEMU’s intended memory model.

I would greatly appreciate any advice or guidance on how to correctly retrieve the data associated with a given PPA within FEMU’s internal architecture, or any recommendations on where such a read operation should be performed to avoid invalid memory access.

Thank you in advance for your time and assistance.