Hi Vilas,
Good point, the workload does need to be defined on both CPUs. That way
they both know what they're running and can setup everything appropriately.
As for the assertion, I wouldn't worry too much about it unless you're
planning on changing memory timing modes between CPUs. If you are, just
make sure you've switched over to Timing mode before using the O3 CPU
(it only works in Timing mode). You're right that the assertion is
useful, but right now the O3 CPU doesn't take a pointer to the System
object in SE mode (an oversight on our part). We'll try to fix this for
the future.
The switchCpus function does replace fast-forwarding. You can handle
doing fast-forwarding totally via your script now. Your script directs
how long to simulate M5, and when to switch between models (like in the
example on the FAQ page). You can use standard loops in Python to have
it repeat as many times as desired. Just be sure that when switching
models back you change the order that they're in the list -- they're
always in tuples (oldCPU, newCPU), where old CPU is the currently
running CPU and newCPU is the CPU you want to switch in.
Kevin
Vilas Sridharan wrote:
Hello all,
I'm fairly new to M5, but was watching this thread with interest since
I am trying to do something similar to James (but in syscall emulation
mode). Thanks, Kevin, for the explanation - this seems to work,
although I believe in SE mode the 'workload' parameter needs to be set
for both CPUs as well (at least, I need to do so in order to get it to
run).
One further question related to doing this in SE mode:
When trying to switch in the O3 CPU model, it reliably core-dumps in
the resume() function, at the assert statement on line 821 of
src/cpu/o3/cpu.cc. It appears that the 'system' object is referenced,
but is only defined in FS mode. For now I've commented out the
assert, but I wanted to know whether there's a more robust fix (the
assert seems important).
Incidentally, I assume the switchCpus function essentially takes the
place of 'fast-fowarding' (eg, in SimpleScalar), since I don't see any
other way to do this?
Thanks,
-Vilas
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