Intel® Virtualization Technology FlexMigration (Intel® VT FlexMigration) allows virtualization software vendors to deliver live migration solutions across different generations of Intel® Xeon® processor-based servers. By dramatically enlarging the generation of servers that can be deployed in a virtual machine (VM) migration compatibility resource pool, Intel VT FlexMigration lets IT managers and CIOs quickly adopt emerging usage models like load balancing and business continuity during unforeseen spikes in data center resource demand. It also helps organizations protect their investments by using both older-generation and new-generation servers in the same resource pool. This white paper explains how Intel VT FlexMigration works, including how and why some instructions are masked by the hypervisor while others are not.