Re: [Qemu-devel] how to convert guest virtual address to host virtual address in QEMU?

[Gunasekaran Dharman <guna.spam@gmail.com>]

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Hi Stefan

Thanks for your valuable suggestion.

I will try the custom memcpy instruction. I have a question regarding
virtual machine's CPU frequency.
Compared to real processor how QEMU is emulating the processor speed?
Can we configure the virtual machine's CPU frequency? If yes, what are the
limitations and impact
of changing the CPU frequency.

Regards
Guna


On Wed, Mar 9, 2011 at 4:57 PM, Stefan Hajnoczi <stefanha@gmail.com> wrote:

> On Wed, Mar 9, 2011 at 9:34 AM, Gunasekaran Dharman <guna.spam@gmail.com>
> wrote:
> > Regarding calculating host virtual address from guest virtual address, I
> > think, QEMU must be doing this somehow.
> > I would like to know how QEMU is handling the guest virtual address?
> > It will be very much helpful if you can throw some light on this.
>
> Sorry but I've tried to explain twice that this approach is not the
> way to go.  The hardware does not necessarily know how to translate
> any virtual address by itself and QEMU doesn't either, guest
> assistance may be required.  It's not as simple as handing a (kernel
> or userspace?) virtual address to a custom device and having it
> perform a memcpy.
>
> If you really want to do a custom hack try adding a custom memcpy
> instruction and look at how x86 targets rep; mov or other instances of
> memory copy on other architectures are done.  You'll need to write a
> custom memcpy implementation in the guest to make use of this
> function.
>
> Stefan
>

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