# Stage Folding Under Virtualization Stage folding occurs when a guest system’s lower layers become ordinary state controlled by a host or hypervisor. ## Model To the guest, firmware, boot order, disks, virtual devices, and TPM state occupy familiar low stages. To the host, those same things may be files, configuration records, snapshots, and service objects at the virtualization layer. ## Evidentiary rule For every virtualized system, record whether evidence came from inside the guest or from the host. In-guest evidence can describe the guest’s presented state but cannot, by itself, establish the integrity or history of the host-supplied substrate. ## Source [[Index - Stages of Interception#The virtualized pre-OS boundary — where Stage 3 folds into Stage 7|The virtualized pre-OS boundary]] · [[Alternative Execution Environment]] · [[Pre-OS Trust Boundary]].