Re: [Qemu-devel] QEMU extension

[Paul Brook <paul@codesourcery.com>]

On Thursday 26 May 2005 17:12, G Portokalidis wrote:
> Hello,
>
> I'm writing concerning a possible use for qemu in a project related to
> network security.
>
> I'm looking for an emulator where I could load an entire (recent) OS,
> like Linux 2.6 or Windows XP and run multiple, potentially CPU
> intensive, services (IIS, Apache, MySQL, etc).
>
> For the needs of the project I need to be able to know every instruction
> executed by the guest OS, and run custom code whenever an instruction of
> particular interest appears (doesn't really matter whether it's C or
> x86, but preferably the first).
>
> So my first question is whether we could run Linux 2.6 and most
> importantly Windows XP on qemu without stability issues. 

Linux works fine. For windows XP it seems to depend which windows version 
you're using. Some versions work ok, others don't.

> Second, does 
> the current design of qemu allows me to implement the functionality
> described in the above paragraph.

You may be better using bochs. That has instrumentation hooks that should 
allow you do do what you want. boch is significantly slower that qemu, but if 
you're instrumenting a significant number of instructions it's going to be 
dog slow anyway.

Qemu already has infrastructure for a gdb ICE connection. You could probably 
hack that to do what you want.

> Finally, what's the performance of qemu compared with a PC (how many
> times slower)?

It's generally 10-15x slower than the host.

Paul