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Re: [Qemu-devel] [RFC] save/restore with icount enabled.
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [RFC] save/restore with icount enabled. |
Date: |
Wed, 15 May 2013 14:50:37 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130311 Thunderbird/17.0.4 |
Il 15/05/2013 11:31, KONRAD Frédéric ha scritto:
> Hi,
>
> We are trying to do a simple save/restore on the VM with icount enabled.
>
> We saw that qemu_icount_bias and qemu_icount in cpus.c are not
> saved/restored,
> and icount_extra, icount_decr in CPUState neither, so the vm_clock is just
> growing normally after restoring the VM is that normal?
>
> We think that this is making the "replay" undeterminastic, which is bad for
> reverse execution.
>
> Is there a good reason for them not being saved?
No. You can probably move icount to timers_state. Something like
zeroing qemu_icount in cpu_disable_ticks() is required in order to save
qemu_icount_bias like the other members of timers_state. There is even
a dummy field that you can reuse to avoid the pain of adding a
subsection to vmstate_timers. :)
Paolo
>
> Thanks,
> Fred
>
>