What exactly is a virtual machine? What does a virtual machine monitor do? And how do we now whether a given piece of hardware can support virtualization or not? There are currently a number of viewpoints suggesting what a virtual machine is, how it ought to be constructed, and what hardware and operating system implications result….
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We think you have liked this presentation. If you wish to download it, please recommend it to your friends in any social system. Share buttons are a little bit lower. Thank you! Published by Pierce Miller Modified over 4 years ago. Popek and Robert P. A virtual machine monitor VMM is a piece of software which Provides an environment for programs that are identical with the original machine Allows programs to run an environment such that decrease in speed is insignificant Occupies the complete control of system resources.
The machine can exist in any one of a finite number of states where each state has four components. User mode: The complete instruction repertoire is not available to the processor.
Each PSW is assumed to be recorded in one storage location. E is assumed to store old-PSW. E is assumed to store new-PSW.
A trap automatically saves the current state of the machine and passes control of a pre- specified routine by changing M, R, P to the values specified in new-PSW location. There are two types of sensitive instruction Control sensitive Behavior sensitive. An instruction is behavior sensitive if the effect of its execution depends on the value of the relocation register R , or the mode M.
Mode sensitive: An instruction is mode sensitive if its execution behavior depends on the mode of previous instruction space. There exists one interpreter routine per privileged instruction. All innocuous instructions are executed by the hardware directly. All innocuous instructions are executed without intervention on the part of the control program. An arbitrary program can not effect the system resources, i.
The allocator of the control program is to be invoked upon any attempt to effect system resources. More specifically, a program K executing with a CP resident performs in a manner indistinguishable from the case when CP does not exist.
Resource availability The allocator does not satisfy a request to attempt to change relocation register R. It is composed of the original real machine and the VMM. Intuitively, a machine is recursively virtualizable, if The virtual machine system can run under itself a copy of the VMM so that the copy exhibits all the properties of VMM. Procedure 1 can be repeated until the resources of the system are consumed. Smith, et al. The definition of third generation architecture has been relaxed to more general, but less efficient form that is labeled as hybrid virtual machine HVM system.
More instructions are interpreted rather than being directly executed in HVM. User sensitivity is only applicable in user mode. Intuitively, the user sensitive instructions are the instructions that cause difficulty when executed from user mode.
Supervisor sensitivity is only applicable in supervisor mode. Necessary and sufficient conditions have been derived to determine whether a third generation machine can support VMM. Popek, R. ACM, vol. Goldberg Honeywell. Interrupts contd.. Some or all of these devices may be capable of generating.
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Popek and Goldberg virtualization requirements
VMM definition[ edit ] System virtual machines are capable of virtualizing a full set of hardware resources, including a processor or processors , memory and storage resources and peripheral devices. A virtual machine monitor VMM, also called hypervisor is the piece of software that provides the abstraction of a virtual machine. In the terminology used in the reference book of Smith and Nair , VMMs are typically assumed to satisfy the equivalence and resource control properties, and those additionally meeting the performance property are called efficient VMMs. Their analysis derives such characteristics using a model of "third generation architectures" e. This model includes a processor that operates in either system or user mode, and has access to linear, uniformly addressable memory. It is assumed that a subset of the instruction set is available only when in system mode and that memory is addressed relative to a relocation register.
FORMAL REQUIREMENTS FOR VIRTUALIZABLE THIRD GENERATION ARCHITECTURES PDF
The Popek and Goldberg virtualization requirements are a set of conditions sufficient for a computer architecture to support system virtualization efficiently. They were introduced by Gerald J. Popek and Robert P. System virtual machines are capable of virtualizing a full set of hardware resources, including a processor or processors , memory and storage resources and peripheral devices. A virtual machine monitor VMM, also called hypervisor is the piece of software that provides the abstraction of a virtual machine. There are three properties of interest when analyzing the environment created by a VMM: .
Formal Requirements for Virtualizable Third Generation Architectures