Hi Adam,
Thank you very much for your reply and suggestions. I have tried making changes according to your recommendations, but they did not seem to take effect.
However, I have discovered something interesting:  when disabling forced mapping and using the method I mentioned in my previous email, the virtual device is able to read the content that the kernel writes to that address range. 
As described in the documentation£º
-i, --ram-identity-mapping
When set, the option forces the guest RAM to be mapped to its corresponding host-physical addresses.
Flag. True if provided.

Additionally, I found that even with forced mapping enabled, the physical address seen by the guest is different from that seen by the host, with an offset between them.The host sees the address as 0x66200000, while the guest sees it as 0x66400000.Based on the code mentioned earlier, this issue can be resolved simply by accounting for this offset during the mapping process.
BR, Stephen