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In this presentation, I introduce research that I worked on as a Ph.D. student. The research is for live migration of operating systems (OS) in Bare-metal clouds, which are IaaS clouds providing physical machines instead of virtual machines. In the IaaS clouds, OS live migration, a function to move running OS from a physical machine to another physical machine, is an important function for machine maintenance. Because commodity OS live migration is achieved by machine virtualization, current bare-metal clouds do not support live migration. Previous studies have proposed OS-level live migration; however, live migration should be OS-independent for preventing user intervention and broaden OS choices in IaaS clouds. To achieve OS-independent live migration without device virtualization, we introduce a very thin hypervisor that exposes physical hardware devices to the guest OS directly rather than virtualizing them. The hypervisor captures, transfers, and reconstructs physical device states by monitoring access from the OS and controlling the physical devices with some techniques. Whenever it does not perform live migration, the hypervisor is mostly idle to minimize performance degradation. A performance evaluation confirmed that the OS performance with the hypervisor is comparable to that of a bare-metal machine.