Re: [Qemu-devel] About address mapping between host and guest in QEMU

[Christopher Covington <cov@codeaurora.org>]

Hi Brendan,

On 04/24/2015 03:50 PM, Brendan Dolan-Gavitt wrote:
> One possible option that has come up in the past is disabling the TLB
> for your testing. It is slower, though, and would only work on TCG,
> not KVM.
> 
> The way I'm currently doing this is by changing the conditional jump
> here to an absolute one inside of the TCG code generator for i386 (and
> of course you can do something similar on other archs). The code here
> has changed since I last looked at it, but this is roughly the place
> to look:
> 
> https://github.com/qemu/qemu/blob/master/tcg/i386/tcg-target.c#L1222
> 
> Depending on your needs, you might want to also look at (shameless
> plug) PANDA [1], which provides callbacks and a plugin architecture
> for many things that happen in QEMU, including memory accesses. You
> can see how we implement the memory callback here:
> 
> https://github.com/moyix/panda/blob/master/qemu/tcg/i386/tcg-target.c#L1079

This is neat. How do you see the relationship with upstream? Will you ever
upgrade QEMU versions?

Have you seen Pavel Dovgalyuk's upstream work on deterministic replay to
enable reverse execution? Does it differ fundamentally from PANDA record and
replay?

It looks like you're running K-means on your QEMU traces. I happen to be doing
that too. Do you happen to have any code examples of that included in PANDA or
other open source projects?

Thanks,
Chris

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