Why doesn't the Linux kernel see the cache sizes in the gem5 emulator in full system mode?

Question

I want to play around with cache sizes in my gem5 simulator to see how it affects performance of programs, and possibly tune programs at runtime.

As a sanity check,

Answer 1

I have been told that:

gem5 doesn't implement the cache size discovery registers.

The problem is that it is really hard to configure them in the general case, and they might not even be able to represent the hierarchy in gem5.