Il 28/05/2014 16:21, James Hogan ha scritto:
The implementation in QEMU that I've settled upon makes do with just COUNT_CTL and COUNT_RESUME, but with a slight kernel modification so that COUNT_RESUME is writeable (to any positive monotonic nanosecond value <= now). It works fairly cleanly and correctly even with stopping and starting VM clock (gdb, stop/cont, savevm/loadvm, live migration), to match the behaviour of the existing mips cpu timer emulation, so I plan to drop this bias patch, and will post a v2 patchset soon with just a few modifications.
It makes sense to have writable registers in the emulator, even if they are read-only in real hardware. We also do that for x86, FWIW.
So the idea looks okay to me. Paolo
