Changes between Version 22 and Version 23 of VirtualBox architecture

Timestamp:

Dec 26, 2006 6:41:29 PM (17 years ago)

Author:

jose

Comment:

--

VirtualBox architecture

@@ -72 +72 @@
 
 
-== Intel VT-x ("Vanderpool") support == 
+== Intel VT-x ("Vanderpool") and AMD-V (SVM) support == 
 
 With its latest processors, Intel has introduced hardware virtualization support, which they call "Vanderpool", "IVT", "VT-x", or "VMX" (for "virtual machine extensions"). As we started out rather early on this, we internally use the term "VMX". A thorough explanation of this architecture can be found on [http://www.intel.com/technology/itj/2006/v10i3/1-hardware/5-architecture.htm Intel's pages], but as a summary, with these extensions, a processor always operates in one of the following two modes:
@@ -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.
 
-So far, we don't support AMD's equivalent to VT-x (called SVM) yet but this is work in process. As you have read above, VT-x support is not of high practical importance and therefore it's not our top priority.
+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.