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From: palutke.ralph@gmx.de
To: xen-devel@lists.xen.org
Subject: how to check for already existing hypervisor?
Date: Thu, 21 Jun 2012 02:44:48 +0200	[thread overview]
Message-ID: <20120621004447.GA12981@mean_maschine.fritz.box> (raw)

Hi guys, 

let me shortly introduce myself. I'm a student and recently work on my bachelor thesis. My goal is to write a little hypervisor.
I'm not quite sure if this is the right mailing list, but i guess you'll gonna tell me.
i have two quick questions:

1. before i can use the vmxon instruction i do have to set vmxe flag in cr4 register. but what if some hypervisor is already running? is there a way to check 
if one is running??

2. before i set the vmxe bit in cr4, i check if it is already enabled. i do this while my module gets loaded. but i observed a strange thing. sometimes
the vmxe bit seems to be set while the other time it isn't. do you have any explanation for that behaviour? do i have to check if the bit is set before 
actually setting it? I've looked at a few hypervisor projects and it seems that no one does it. my primary thought was, if the bit is set a hypervisor is running, 
but i don't think that's true anymore. so do i need the check?

greetings 

             reply	other threads:[~2012-06-21  0:44 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-06-21  0:44 palutke.ralph [this message]
2012-06-25  9:07 ` how to check for already existing hypervisor? Tim Deegan
  -- strict thread matches above, loose matches on Subject: below --
2012-06-20 23:00 palutke.ralph

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