I've been trying out gem5 for the first time these past few days, but so far I've found the process pretty easy to pick up on.
However, I have a question about creating checkpoints when using the MOESI CC protocol. Earlier posts on the mailing list this month seemed to indicate that the MOESI_hammer protocol could be checkpointed, but that other Ruby protocols had trouble (Nilay Vaish | 25 Mar 15:54). Is this still current? With a very recent checkout, the following simulation boots fine (though it takes 48 hours to boot the kernel), but when I tried to run `m5 checkpoint`, the simulator exited. Very unfortunately, I don't have the stdout or stderr of the gem5 process, which I realize would be critical to debugging this particular problem. M5_PATH=. ../gem5.hammer.fast -d hammer ../configs/example/ruby_fs.py --ruby --cpu-type=timing --caches -n 64 --kernel=x86_64-vmlinux-2.6.28.4-smp I used the kernel from utexas' PARSEC page, the disk image is the unmodified example image from http://www.m5sim.org/dist/current/x86/x86-system.tar.bz2 The binary was built with the following built_opts: TARGET_ISA = 'x86' CPU_MODELS = 'AtomicSimpleCPU,O3CPU,TimingSimpleCPU' PROTOCOL = 'MOESI_hammer' After the checkpoint, I appear to have m5.cpt and two COW disks. However, running the above command with '-r 1' to resume causes a debug assertion failure when a CPU is missing an interrupt controller. I know I'm in uncharted waters with X86 FS with Ruby, but it "Should Work", and I've seen casual traffic of other users running the PARSEC benchmarks on X86 FS. a) Any clue why my MOESI_hammer checkpoints are failing and crashing? b) How hard would it be and what roughly would be required to get checkpointing working with other CC protocols, like MOESI_CMP_directory? c) Is it possible to create a checkpoint with the AtomicCPU and Classic memory, then resume with a more detailed CPU and memory system, assuming all cache sizes and memory stayed the same? Thanks, -Mark Browning Texas A&M
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