Changes between Version 4 and Version 5 of VirtualBox_architecture

Timestamp:

Sep 28, 2008 11:41:10 AM (16 years ago)

Author:

Sander van Leeuwen

Comment:

--

VirtualBox_architecture

@@ -83 +83 @@
 In non-root mode, the processor will automatically cause VM exits for certain privileged instructions and events. For some of these instructions, it is even configurable whether VM exits should occur. 
 
-Since, however, nearly all operating systems in use today only make use of ring-0 and ring-3, and since a lot of operations in non-root mode are very expensive, !VirtualBox does not use VT-x exactly as intended by Intel. Instead, we make partial use of it -- only where it makes sense and where it helps us to improve performance. So, as said above, our hypervisor, on non-VT-x machines, lives in ring 0 of the guest context, below the guest ring-0 code that is actually run in ring 1. When VT-x is enabled, the hypervisor can safely live in ring 0 ''host'' context and gets activated automatically by use of the new VM exits.
+As said above, our hypervisor, on non-VT-x machines, lives in ring 0 of the guest context, below the guest ring-0 code that is actually run in ring 1. When VT-x is enabled, the hypervisor can safely live in ring 0 ''host'' context and gets activated automatically by use of the new VM exits.
 
-We also have experimental support for AMD's equivalent to VT-x (called AMD-V or SVM). As you have read above, VT-x support is not of high practical importance and we have noticed that our implementation of AMD-V is currently even slower than VT-x. Over time we plan to improve it but it's not our top priority right now.
+We also fully support for AMD's equivalent to VT-x (called AMD-V or SVM). This includes the nested paging feature in the Barcelona level CPUs (Phenoms and newer Opterons). 
 
 == Advanced techniques: code scanning, analysis and patching ==