Compaq BL10e - HP ProLiant - 512 MB RAM Introduction Manual page 19

Hosted OS, kernel-layer abstraction
Kernel-layer abstraction refers to a technique in which the abstraction technology is built directly into
the OS kernel rather than having a separate hypervisor layer. This approach can still follow the
requirements of hardware-assisted (AMD-V or Intel VT-x virtualization technologies) and
paravirtualization, but removes the discrete hypervisor layer. The direct access to hardware could
potentially provide greater performance than using a binary translation technology; however,
because there is no separation between the hypervisor the operating system, there is the possibility
that resource conflicts may occur between multiple virtual machines.
See the article titled ―Xen proponents question merits of Red Hat KVM hypervisor‖ at
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http://searchservervirtualization.techtarget.com/news/article/0,,sid94_gci1318772,00.html; and for the opposing view,
see Qumranet's white paper titled ‖KVM - Kernel-based Virtualization Machine‖ at
www.qumranet.com/files/white_papers/KVM_Whitepaper.pdf.
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