Virtual Machines

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phy_lbc
Posts: 15
Joined: Sat Nov 21, 2009 4:32 pm

Virtual Machines

Post by phy_lbc »

Does VMware have a hardware accelerated program you can install on to the host operating system to improve the speed of ReactOS (or any other virtualised OS) while it is in a virtual machine. For qemu there is kqemu. Is there anything similar to that for any other virtual machines?

Many thanks
gabrielilardi
Moderator Team
Posts: 873
Joined: Sat Sep 02, 2006 1:30 am
Location: Italy

Re: Virtual Machines

Post by gabrielilardi »

phy_lbc wrote:Does VMware have a hardware accelerated program you can install on to the host operating system to improve the speed of ReactOS (or any other virtualised OS) while it is in a virtual machine. For qemu there is kqemu. Is there anything similar to that for any other virtual machines?

Many thanks
Qemu is one of the slowest emulators, virtualbox is based off of it but greatly improved, vmware and virtualbox are amongst the fastest emulators, they don't need kemu or something similar cause they use their own services that speed up emulation. You can install guest additions though in both emulators to improve user experience and enable some extra features (general chat, no ros related).
cppm
Posts: 289
Joined: Wed May 02, 2007 10:03 pm

Re: Virtual Machines

Post by cppm »

I'd like to explore what you mean by 'hardware accelerated' I think you mean that they allow native execution.

My understanding is that VMWare already uses native execution by default. This means that when VMWare runs a VM it runs it on the native hardware but catches and translates only a small subset of instructions that would otherwise prove problematic. This naturally allows for quite a speedup, and for certain tasks allows near native speeds.

Qemu performs full binary translation by default, therefore it catches and translates everything (I think even the term 'catching' might be wrong in this sense), this makes a certain sense from an architectural point of view since one of Qemu's aims is to provide a wide range of host and guest OS support, parallel either way (if it supports a certain host, then it'll support all guests and vice versa).

KQemu is an attempt to allow a certain amount of native execution in Qemu, however naturally it doesn't work on all hosts, and it will only work if you are emulating the same hardware as the host. I do not know how well native execution works in KQemu as compared with VMWare.

If what i've said here is correct, it would be completely redundant for there to be an acceleration module for VMWare that does what KQemu does for Qemu, since VMWare already does it anyway. I hope that answers your question. :)

With regards to Virtual Box; I don't know. I should imagine that since this is a product that's supposed to be more 'polished' than Qemu it'll attempt to perform native execution when it thinks its appropriate, but I really don't know.

Ars Technica have some great guides to virtualisation if you're looking for an accessible exploration of this. :)
phy_lbc
Posts: 15
Joined: Sat Nov 21, 2009 4:32 pm

Re: Virtual Machines

Post by phy_lbc »

Thanks for the replies. I only tried XP on VMWare, and it wasn't too speedy. I was comparing the speed of ReactOS using kqemu and Windows XP using VMware. I thought that all VM's did full binary translation and that qemu was an exception, thanks for clearing that up for me. Now that I've tried ReactOS on VMware, I can say that it is very very fast. I guess I was comparing apples with oranges there.
cppm
Posts: 289
Joined: Wed May 02, 2007 10:03 pm

Re: Virtual Machines

Post by cppm »

Yeah - try running XP in vanilla Qemu if you want to see slow ;)
Aeneas
Posts: 471
Joined: Sat Oct 10, 2009 10:09 pm

Re: Virtual Machines

Post by Aeneas »

I just wanted to share what I saw... my jaw hit the floor, ReactOS on Qemu on FreeDOS, some day this has to be tried!

http://qemu-forum.ipi.fi/viewtopic.php?f=26&t=3211
JPLR
Posts: 80
Joined: Tue Oct 14, 2008 4:58 pm

Re: Virtual Machines

Post by JPLR »

Hi,

HX Dos extender is a fantastic piece of code, but it runs only one console/window at a time. It happens that Qemu is a Windows console application so it runs under HX. And when Reactos wants to access graphics it's the SDL layer on HX that is used. But the nice thing is indeed that Reactos is a good Win32 platform so there is really an added value to have Reactos on Qemu on HX on DOS.
The good thing is that there is now support for USB on DOS with source code at: http://www.bretjohnson.us/
There is also support for some WIFI cards under DOS now.

Have a nice day,
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