Changes between Version 3 and Version 4 of VirtualBox_architecture

VirtualBox_architecture

v3	v4
85	85	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.
86	86
87		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 ~~AMD's implementation comes with an even larger performance penalty plus a number of implementation errors, improving our support for ADM-V is currently not the most important item~~.
	87	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.
88	88
89	89	== Advanced techniques: code scanning, analysis and patching ==