《Operating System Concepts》學習第 60 天，p700-p732 總結，總計 33 頁。

一、技術總結

1.Virtual machine manager (VMM)

The computer function that manages the virtual machine; also called a hypervisor.

VMM 也稱為 hypervisor。

2.types of VMs

type 0 hypervisor、type 1 hypervisor、type 2 hypervisor。

3.bridging

The guests can be “directly” connected to the network by an IP address that is seen by the broader network (this is known as bridging).

二、英語總結(生詞：3)

1.permeate

(1)permeate: per-("forward", hence "through") + *mei-("to go, move")

vi/vt. permeate literally means go through. to spread through and be present in every part of it(滲透)。

(2)示例

Virtualization permeates all aspects of computing(《Operating System Concepts》第 700 頁)。

(3)permeate vs pervade

暫時沒看到明顯的區分標準，TBD。

2.illusion

(1)illusion:in-("in") + ludere("to play")

c/u. a false perception(感知，感覺) by the senses(錯覺，幻覺)。

(2)示例

The fundamental idea behind a virtual machine is to abstract the hardware of a single computer (the CPU, memory, disk drives, network interface cards, and so forth) into several different execution environments, thereby creating the illusion that each separate environment is running on its own private computer(《Operating System Concepts》第 701 頁)。

3.leeway

(1)leeway: lee("a nutical term meaning the sheltered side of a ship(the side away from the wind)") + way("movement")

u. originally, leeway described how much a ship drifted sideways(dowawind) due to wind or currents(最初，“leeway”描述的是由于風或洋流，船只側向（順風）漂移的程度)。freedom to act within particular limits()。

(2)示例

In the area of I/O, hypervisors have some leeway and can be less concerned with how they represent the underlying hardware to their guests(《Operating System Concepts》第 722 頁)。

關于英語的注解同步更新匯總到 https://github.com/codists/English-In-CS-Books 倉庫。

三、其它

第 18 章(Virtual Machines)簡評：關于虛擬機，作為開發而言，可能相對更熟悉 example(如：VMWare Workstation, Oracle VirtualBox)。

四、參考資料

1. 編程

(1) Abraham Silberschatz，Peter Baer Galvin，Greg Gagne《Operating System Concepts》：https://book.douban.com/subject/30272539/

2. 英語

(1) Etymology Dictionary：https://www.etymonline.com

(2) Cambridge Dictionary：https://dictionary.cambridge.org

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