[Qemu-devel] Monitoring memory writes

[Igor R]

In my QEMU-based project I would like to perform "extensive" tracing
of basic blocks (translation blocks). I.e. in addition to what the
existing tracing mechanism does, I'd like to log registers modified by
TB and memory (RAM) written by TB. As for registers, it seems to be
trivial. My main problem is how to know what memory addresses/sizes
were written by a TB.
During the research of this subject I found the following thread:
https://lists.gnu.org/archive/html/qemu-devel/2015-04/msg00944.html
The bottom line, IUUC, is that the only way to get what I need is to
disable the "fast path" of the memory accesses. However, I still can't
realize how to modify the back-end correctly. Besides, I would like to
be able to enable/disable the fast path at run-time - to minimize
impact on the performance when the tracing is not enabled. Would it be
possible?
I'd appreciate any pointer!


Thanks.