Nice catch by Andrew Dugdell: it’s about 10 years ago that Scott Devine, Edouard Bugnion and Mendel Rosenblum filed patent #6397242, “Virtualization system including a virtual machine monitor for a Computer with segmented Architecture”.
Filing date: Oct 26, 1998
Issue date: May 28, 2002
Inventors: Scott W. Devine, Edouard Bugnion, Mendel Rosenblum
Assignees: VMWare, Inc.
Primary Examiner: Majid Banankhah
Attorney: Jeffrey Slusher
Application number: 9/179,137
In a computer that has hardware processor, and a memory, the invention provides a virtual machine monitor (VMM) and a virtual machine (VM) that has at least one virtual processor and is operatively connected to the VMM for running a sequence of VM instructions, which are either directly executable or non-directly executable. The VMM includes both a binary translation sub-system and a direct execution sub-system, as well as a sub-system that determines if VM instructions must be executed using binary translation, or if they can be executed using direct execution. Shadow descriptor tables in the VMM, corresponding to VM descriptor tables, segment tracking and memory tracing are used as factors in the decision of which execution mode to activate. The invention is particularly well-adapted for virtualizing computers in which the hardware processor has an Intel x86 architecture.