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Optimization levels under Virtual PC

On a running virtual machine (under Virtual PC) you can see the optimization level being used by selecting 'Properties' off of the 'Action' menu - and then going to the 'Advanced' tab.  There are three possible optimization levels:

  1. None: You should only ever see this if you are using the '-disableopt' command line option - and you would only ever want to do this for debugging purposes.

  2. User mode optimization enabled: This is the default mode of operation for virtual machines.  User mode code (or ring 3) is run directly on the processor - but kernel mode code (or ring 0) is handled inside of a binary translator.

  3. User and kernel mode optimizations: In this mode both user and kernel mode code is run directly on the processor.  This mode is only enabled on certain operating systems (windows NT, 2000, XP, 2003, Vista) once Virtual Machine Additions have been loaded.

Cheers,
Ben

Published Tuesday, March 14, 2006 7:31 PM by Virtual PC Guy

Comments

Wednesday, March 15, 2006 10:19 AM by Nelson

# re: Optimization levels under Virtual PC

If ring 0 code is allowed to run directly on processor, how can VPC prevent the guest from using the real hardware directly ?
Wednesday, March 15, 2006 7:18 PM by Garth Ruthindale

# re: Optimization levels under Virtual PC

We're watching you...
Wednesday, March 15, 2006 10:37 PM by Mike (Ben's boss)

# re: Optimization levels under Virtual PC

We use ring compression to run the guest ring 0 code at ring 1.  Check out my channel 9 video:

http://channel9.msdn.com/ShowPost.aspx?PostID=163022

-Mike
Thursday, March 16, 2006 9:41 AM by James Risto

# re: Optimization levels under Virtual PC

Amazing that you can get (practically) any OS, that thinks its at ring 0, to run at ring 1.
Monday, March 27, 2006 9:14 PM by jclin::Wordpress » Blog Archive » x86 Virtual PC

# jclin::Wordpress » Blog Archive » x86 Virtual PC

Thursday, December 28, 2006 5:15 PM by Jose Aguilar's Blog

# On Virtual Machine Additions

Several times I've been asked something along the lines of “why should I install virtual machine additions on a virtual machine? The virtual machine works fine without them, doesn't it?". I thought it is worth it to quickly mention why you should always

Monday, April 07, 2008 4:58 AM by Say what? Microsoft Malaysia One ISV Technology Blog

# Arrghh, why does Virtual PC technology exist in the first place?

LOL, I reckon that a blog post title like this is sure to attract your attention to read this. My apologies,

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