Virtualization Fundamentals
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Questions and Answers

What was the primary motivation behind the development of virtualization in the 1960s?

  • To reduce the cost of mainframe computers
  • To simplify the management of business services
  • To increase the processing power of individual users
  • To enable concurrent running of diverse workloads on the same physical hardware (correct)

    • What is the term for the combination of an operating system, its applications, and its virtual resources?

  • Guest domain
  • Hypervisor
  • Virtual resource
  • Virtual machine (correct)

    • What is the primary function of the virtualization layer?

  • To manage the allocation of real hardware resources
  • To provide isolation guarantees across VMs
  • To support the coexistence of multiple VMs and provide isolation guarantees (correct)
  • To enable multiple VMs to exist on a single physical machine

    • What is the term for the underlying functionality that enables virtual machines to exist?

    <p>All of the above</p> Signup and view all the answers

    What is a virtual machine, according to the definition?

    <p>An efficient, isolated duplicate of a real machine</p> Signup and view all the answers

    What is the term used to refer to the operating systems that are deployed on the same physical platform?

    <p>Either A or B</p> Signup and view all the answers

    Which company has the largest share of server cores and has mandated device manufacturers to develop drivers that can be used by the hypervisor?

    <p>VMware</p> Signup and view all the answers

    What is the primary responsibility of a VMM in terms of hardware representation?

    <p>To ensure that the VM's hardware representation matches the physical platform's hardware</p> Signup and view all the answers

    What is the goal of the VMM in terms of performance?

    <p>To provide performance to VMs that is as close to native performance as possible</p> Signup and view all the answers

    What type of virtualization model uses a full-fledged host OS that manages all of the hardware resources?

    <p>Hosted</p> Signup and view all the answers

    What is the benefit of consolidation in virtualization?

    <p>To decrease cost and improve manageability</p> Signup and view all the answers

    What is the benefit of the hosted model in terms of functionality development?

    <p>It requires less functionality to be developed for the VMM module.</p> Signup and view all the answers

    What is the advantage of virtualization in terms of migration?

    <p>It makes setup, teardown, and cloning of virtual machines easier</p> Signup and view all the answers

    What is the purpose of the QEMU hardware emulator in the KVM setup?

    <p>To act as a virtual interface between the VM and the physical hardware.</p> Signup and view all the answers

    What is the advantage of virtualization in terms of availability and reliability?

    <p>It allows easy spin up of new VMs on a different physical platform in case of a failure</p> Signup and view all the answers

    What is the main advantage of the KVM virtualization solution?

    <p>It can quickly adapt to new features and fixes.</p> Signup and view all the answers

    What is the primary responsibility of the VMM module in the hosted model?

    <p>To provide a virtual platform interface to the guest VMs.</p> Signup and view all the answers

    What is the purpose of a service VM in bare-metal virtualization?

    <p>To run device drivers and control hardware access</p> Signup and view all the answers

    What is the name of the privileged domain in the Xen virtualization software?

    <p>dom0</p> Signup and view all the answers

    What is the purpose of protection levels in virtualization setups?

    <p>To protect the VMM from the guest OS.</p> Signup and view all the answers

    What is the issue with device drivers in bare-metal virtualization?

    <p>Device manufacturers need to provide drivers for different hypervisors</p> Signup and view all the answers

    What is the term for the process of switching control from the guest OS to the hypervisor in a virtualization setup?

    <p>VMExit</p> Signup and view all the answers

    What is the term for the process of switching control from the hypervisor back to the guest OS in a virtualization setup?

    <p>VMEntry</p> Signup and view all the answers

    What is the primary benefit of virtualization for operating systems research?

    <p>It provides a fertile ground for testing and development</p> Signup and view all the answers

    What is the advantage of virtualization for supporting legacy operating systems?

    <p>It provides affordable support for legacy operating systems</p> Signup and view all the answers

    What happens when a privileged instruction is issued by the guest OS?

    <p>The processor causes a trap to the hypervisor.</p> Signup and view all the answers

    What was the issue with the 17 hardware instructions in x86 platforms before 2005?

    <p>They didn't cause a trap to the hypervisor, but failed silently.</p> Signup and view all the answers

    What is the goal of binary translation?

    <p>To run unmodified guest operating systems.</p> Signup and view all the answers

    What is done to the code blocks that contain one of the 17 hardware instructions in binary translation?

    <p>They are translated into alternate instruction sequences.</p> Signup and view all the answers

    What is the main difference between full virtualization and paravirtualization?

    <p>Full virtualization requires modified guest OSes, while paravirtualization doesn't.</p> Signup and view all the answers

    What are the hypercalls similar to in paravirtualization?

    <p>System calls.</p> Signup and view all the answers

    Why does the guest OS assume that the change was successful when it issues a privileged instruction?

    <p>Because the instruction fails silently.</p> Signup and view all the answers

    What is the purpose of caching translated code fragments in binary translation?

    <p>To reduce the overhead of the virtualization layer.</p> Signup and view all the answers

    What is the consequence of not modifying the guest OS in full virtualization?

    <p>The guest OS can run in a virtualized environment without additional software or policies.</p> Signup and view all the answers

    What is the name of the strategy used by the hypervisor to handle privileged instructions?

    <p>Trap-and-emulate strategy.</p> Signup and view all the answers

    What is a key requirement for full virtualization?

    <p>The guest OS continues to observe a contiguous, linear address space</p> Signup and view all the answers

    What is the purpose of the hypervisor's shadow page table?

    <p>To re-map the virtual addresses to machine addresses without considering physical addresses</p> Signup and view all the answers

    Why does the hypervisor need to write-protect the page table?

    <p>To prevent the guest OS from modifying the page table</p> Signup and view all the answers

    What is the benefit of paravirtualization?

    <p>The guest OS can explicitly register its page tables with the hypervisor</p> Signup and view all the answers

    What is the purpose of the MMU and TLB in memory virtualization?

    <p>To help with address translation and free us from implementing translations in software</p> Signup and view all the answers

    What is the difference between physical addresses and machine addresses?

    <p>Physical addresses are the addresses that the guest thinks are the addresses of the physical resource, while machine addresses correspond to the physical addresses on the underlying physical platform</p> Signup and view all the answers

    What happens when the guest OS tries to establish new address mappings in full virtualization?

    <p>The guest OS traps into the hypervisor</p> Signup and view all the answers

    Why does the hypervisor need to maintain consistency between the two page tables?

    <p>To ensure that the mappings in both page tables are consistent</p> Signup and view all the answers

    What is the advantage of batching page table updates into a single hypercall in paravirtualization?

    <p>It reduces the overhead of the VM exit</p> Signup and view all the answers

    What is the benefit of newer hardware platforms in terms of memory virtualization?

    <p>They reduce the overhead associated with memory virtualization</p> Signup and view all the answers

    What was the primary issue with the initial x86 architecture regarding virtualization?

    <p>It had 17 non-virtualizable hardware instructions</p> Signup and view all the answers

    What is the purpose of a VM control block?

    <p>To capture the state of virtual processors</p> Signup and view all the answers

    What is the benefit of extended page tables and tagged TLBs in virtualization?

    <p>They reduce the overhead of context switches between VMs</p> Signup and view all the answers

    What is the purpose of multiqueue devices in virtualization?

    <p>To allow multiple VMs to share a single device</p> Signup and view all the answers

    What was added to the x86 architecture to support virtualization?

    <p>A new instruction to switch into a new protection mode</p> Signup and view all the answers

    What is the purpose of tagging memory structures with VM identifiers?

    <p>To allow the hardware to differentiate between VMs</p> Signup and view all the answers

    What is the primary concern in the passthrough model of device virtualization?

    <p>Exclusive access to a device making sharing difficult</p> Signup and view all the answers

    Which device virtualization model allows for device sharing and easy migration of guest VMs?

    <p>Hypervisor-direct model</p> Signup and view all the answers

    What is the main benefit of the split device driver model compared to the hypervisor-direct model?

    <p>Elimination of device emulation overhead</p> Signup and view all the answers

    What is the main limitation of the passthrough model in terms of device access?

    <p>Exclusive access to a device</p> Signup and view all the answers

    Which device virtualization model requires modification of the front-end driver?

    <p>Split device driver model</p> Signup and view all the answers

    What is the main benefit of the hypervisor-direct model in terms of device access?

    <p>Decoupling of guest VMs from physical devices</p> Signup and view all the answers

    Which device virtualization model is also known as the VMM-bypass model?

    <p>Passthrough model</p> Signup and view all the answers

    What is the main challenge of the passthrough model in terms of migration of guest VMs?

    <p>Device-specific state that needs to be copied and configured</p> Signup and view all the answers

    Which device virtualization model involves a component that resides in a guest VM and a component that resides in a hypervisor layer?

    <p>Split device driver model</p> Signup and view all the answers

    What is the main benefit of the split device driver model in terms of device management?

    <p>Better management of shared devices</p> Signup and view all the answers

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