Re: QEMU Clock record and replay

[Arnabjyoti Kalita]

Thank you Lukas for your answer.

I was only looking to record and replay host clock values (not any other events), i.e. record in KVM mode and replay in TCG mode.

Best Regards,

Arnab

On Thu, Feb 25, 2021 at 10:00 PM Lukas Straub <lukasstraub2@web.de> wrote:

On Thu, 25 Feb 2021 20:39:20 +0530
Arnabjyoti Kalita <akalita@cs.stonybrook.edu> wrote:

> Hello all,
>
> [...]
>
> - Let's say we record the clock values when the guest starts in KVM mode,
> and we replay the clock values when the guest starts in TCG mode. Does the
> record-replay functionality change a lot?

Record-replay only works in TCG mode, as one needs to intercept rdtsc/wrtsc
instructions (among others) and KVM doesn't support that.

Regards,
Lukas Straub

> - Also, I couldn't understand the specific purpose of replaying the
> 'virtual real time clock' ? Do I still need to record and replay the
> 'virtual real time clock' if we record the clock values in KVM mode, and
> replay the clock values in TCG mode?
>
> Thank you very much.
>
> Best Regards,
> Arnab



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