Patent ID: 7797507

Claim:
A virtual machine system, comprising: a physical memory; and a virtual machine monitor (VMM), when a kernel image of one guest operating system (OS), in startup of said one guest OS, has already been loaded on said physical memory, said VMM starts up one guest OS with said kernel image, said VMM includes a management table representing a state of a kernel image loaded into said physical memory, and said VMM checks whether or not said kernel image of said one guest OS has been loaded on said physical memory based on management table, when said kernel image of said one guest OS, in startup of said one guest OS, is not loaded on said physical memory, said VMM loads said kernel image of said one guest OS on said physical memory, wherein said VMM adds a new entry of said kernel image of said one guest OS on said management table, when said kernel image of said one guest OS is loaded on said physical memory, wherein said VMM checks whether or not said kernel image of said new entry is the same as said kernel image of other entry based on said management table, when there is said other entry except for said new entry, and said management table includes an entry representing a size of said kernel image loaded, said VMM checks by comparing the size of the kernel image of each entry.