Datasheet

Chapter 1: Overview of Virtualization
13
Hypervisor
Hardware
Virtual Machine
or Console
with Administrative
Control
Virtual Machine Virtual Machine
Figure 1-3
Hypervisors are used to support virtual machines in “ paravirtualization, ” “ full virtualization, ”
and “ hardware virtualization ” environments. Depending on the type of hypervisor used and the
specific approach to virtualization that it takes, the source code of the operating system running
in a virtual machine may need to be modified to communicate with the hypervisor. Figure 1 - 4
shows hypervisor - based virtual machines that leverage hardware support for virtualization, but
also require a hypervisor for some types of administrative interaction with the virtual machines.
For more information about hypervisor - based approaches to virtualization and some examples
of virtualization software that uses this approach, see the section “ Server or Machine Virtualiza-
tion ” earlier in this chapter. For details on any of these software packages, see the section “ Other
Popular Virtualization and Emulation Software ” in Chapter 2.
Kernel - level: The Linux kernel runs the virtual machines, just like any other user - space process,
as shown in Figure 1 - 5 . This type of virtualization runs virtual machines whose operating
system, libraries, and utilities have been compiled for the same hardware and instruction set
as the Linux kernel that is running them, which was compiled for the physical machine on
which the virtual systems are running. For more information about this approach to
virtualization and some examples of virtualization software that uses this approach, see the
section “ Server or Machine Virtualization ” earlier in this chapter. For details on any of these
software packages, see the section “ Other Popular Virtualization and Emulation Software ”
earlier in this chapter.
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