硬件保護(hù)和軟件保護(hù)

A computer contains various hardware like processor, RAM, monitor etc. So OS must ensure that these devices remain intact ( not directly accessible by the user).

計算機(jī)包含各種硬件，例如處理器，RAM，監(jiān)視器等。因此，操作系統(tǒng)必須確保這些設(shè)備保持完整(用戶不能直接訪問)。

It is divided into three categories:

它分為三類：

1)CPU保護(hù) (1) CPU Protection)

It means that a process should not hogg (hold) CPU forever otherwise other processes will not get the process. For that purpose, a timer is introduced to prevent such a situation. A process is given a certain time for execution after which a signal is sent to the process which makes the process to leave CPU. Hence process will not hogg the CPU.

這意味著一個進(jìn)程不應(yīng)永遠(yuǎn)占用(保持)CPU，否則其他進(jìn)程將無法獲得該進(jìn)程。 為此，引入了計時器以防止這種情況。 給某個進(jìn)程一定的執(zhí)行時間，之后將信號發(fā)送到該進(jìn)程，使該進(jìn)程離開CPU。 因此，進(jìn)程不會占用CPU。

2)記憶保護(hù) (2) Memory Protection)

There may be multiple processes in the memory so it is possible that one process may try to access other process memory.

內(nèi)存中可能有多個進(jìn)程，因此一個進(jìn)程可能會嘗試訪問其他進(jìn)程內(nèi)存。

To prevent such situation we use two register:

為了防止這種情況，我們使用兩個寄存器：

Base Register

基本寄存器

Limit Register

限價登記

Base register store the starting address of the program and Limit Register store the size of the process. So whenever a process wants to access address in memory then it is checked that it can access the memory or not.

基址寄存器存儲程序的起始地址，而極限寄存器存儲過程的大小。 因此，只要進(jìn)程想要訪問內(nèi)存中的地址，就會檢查該進(jìn)程是否可以訪問內(nèi)存。

3)I / O保護(hù) (3) I/O protection)

To ensure CPU protection OS ensure that below case should not occur

為了確保CPU保護(hù)OS，請確保不會發(fā)生以下情況

• View I/O of other process

  查看其他進(jìn)程的I / O

• Terminate I/O of another process

  終止另一個進(jìn)程的I / O

• Give priority to a particular process I/O

  優(yōu)先處理特定的流程I / O

If an application process wants to access any I/O device then it will be done through system call so that OS will monitor the task.

如果應(yīng)用程序進(jìn)程要訪問任何I / O設(shè)備，則將通過系統(tǒng)調(diào)用來完成，以便OS監(jiān)視任務(wù)。

Like In C language write() and read() is a system call to read and write on file. There are two modes in instruction execute:

像在C語言中一樣， write()和read()是對文件進(jìn)行讀寫的系統(tǒng)調(diào)用。 指令執(zhí)行有兩種模式：

User mode

用戶模式

The system performs a task on behalf of user application this instruction. In this mode, the user cannot directly access hardware and reference memory.

系統(tǒng)代表用戶應(yīng)用程序執(zhí)行此指令的任務(wù)。 在這種模式下，用戶無法直接訪問硬件和參考存儲器。

Kernel mode

內(nèi)核模式

Whenever a direct access to hardware is required a system call is used by the application program.

每當(dāng)需要直接訪問硬件時，應(yīng)用程序就會使用系統(tǒng)調(diào)用。

翻譯自: https://www.includehelp.com/operating-systems/hardware-protection.aspx

硬件保護(hù)和軟件保護(hù)

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