Questions tagged [operating-systems]

Questions about the principles of software that interfaces between hardware and applications.

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How does symlink work?

I am recently studying The Operation System, I am confused about how symlink work even after watching some YouTube videos, hope there's someone can help me out with some questions. According to wiki, ...
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What is the relationship between virtual address and physical address?

I am recently studying the operating system, and I found the paging system a little bit confusing, for example, what will happen when there is a 52-bit virtual address and a 40-bit physical address, ...
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Relationship between an operating system consisting of a single binary and an operating system consisting of multiple binaries [closed]

What is relationship between an operating system consisting of a single binary and an operating system consisting of multiple binaries? For example, Linux distribution and InfiniTime. Now I don't mean ...
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Choices in cpu-scheduling decisions

I'm reading Operating System Concepts by Silberschatz and in chapter 5, there is this text: 1. CPU-scheduling decisions may take place under the following four circumstances: When a process switches ...
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Does the Posix read() system call for FILE* have an internal buffer in the kernel?

Does the answer depend on the number of bytes requested? If it is forced to keep a buffer due to some unknown device/diver, can it optimize and skip the buffer if it's going to be a disk read? I'm ...
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Is booting only a part of OS possible?

I am reading the paper HyperEnclave. I have a few questions about the OS in general. Is is safe to assume that attackers cannot mount physical attacks during boot process of the OS? Can we assume ...
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Can event counters realize critical sections?

Can event counters be used for implementation of critical sections?
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Page/Frame VS Block

I am bit confused on these terminologies. While studying Paging of Operating System we study about Page and Frame. Size of one Frame of Main Memory = Size of one Page of a Process While studying ...
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If a process needs more RAM, does the Page size simply get bigger or does it get a new page?

Let's say I have a Operating System with 4KB page size, but I need to allocate 8kb of memory for all the variables. Does the Process get new page (second one) or does the current page table simply get ...
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What is the difference between segmentation and dynamic partitioning in memory management?

I was reading up segmentation in memory management, and it seems similar to dynamic partitioning. What is the difference between segmentation and dynamic partitioning?
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How are frames split up in an inverted page table?

For an inverted page table, it's number of entries = number of frames in main memory. One frame in the main memory, could be shared by two (or more) processes, say process A and process B. Usually ...
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Saving Process State by Writing Pages to Blocks

Why don’t operating systems save process state (registers, page tables, pages) by writing state to storage in blocks? Wouldn’t this allow for a seamless restoration of state when the process needs to ...
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Combining fork() and algorithms

Today in my algorithms class, my professor explained how in divide and conquer algorithms we do things in "parallel" although I felt it was not exactly in parallel. Then I remembered from OS ...
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Is kernel essentially an implementation of system calls?

In essence, is kernel basically the code that implements a set of system calls?
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Why is this code for dining philosophers deadlock free?

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How do we run programs which are bigger than RAM itself

I know that whenever click on .exe, it will be moved into RAM so cpu can execute machine code line by line. But what if .exe is bigger than RAM? for eg: I play games which take up more space than my ...
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On load estimation of memory consumption of program, is it possible?

In the book "Fundamentos de sistemas operativos" (Gunnar Wolf, Esteban Ruiz, Federico Bergero, Erwin Meza p.254) it says: Al cargar un programa el sistema operativo calcula cuánta memoria ...
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Computer Architecture MIPS assembler with predictors

This MIPS code is given: ...
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Does optimal page replacement cause the same number of faults for the reverse string?

Let $P_1P_2...P_k$ be a page sequence that gives $n$ page faults with the optimal page replacement algorithm. Does the page sequence $P_kP_{k-1}...P_1$ give the same number of page faults. This can be ...
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Execution-time address binding, logical addresses creation

In the operating systems that make use of the execution-time address binding who is responsible for the creation of logical addresses? EDIT I'm thinking that the logical addresses are generated by the ...
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Swapping in mobile systems

I know that swapping is avoided in mobile systems because of limited memory but I came across this question and couldn't answer if the answer is yes. Should swapping be done in Mobile systems? If yes, ...
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Need help to find some courses about system software design and development

The question's title itself says what I want. I've already searched this term on google but I can't find any course with this theme. What terms I can use to search about this course?
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How does the kernel sends information generated by an interrupt to the right process?

Andrew S. Tanenbaum, in his book Modern Operating Systems states that, When a hardware interrupt occurs while a user thread is running, the interrupted CPU switches into kernel mode. If the interrupt ...
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What is the advantage of a hashed inverted page table versus an ordinary hashed page table?

A hashed inverted page table has a hash table that points each page number to its frame number. This frame number can then be used as an index to the inverted page table to get the PID and page number....
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How are interrupts handled?

Andrew S. Tanenbaum, in his book Modern Operating Systems, states that Once the CPU has decided to take the interrupt, the program counter and PSW are typically then pushed onto the current stack and ...
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Questions regarding Translation Lookaside Buffer (TLB)

TLB is used in the paging memory scheme to reduce the time taken for memory access for a user's memory location through storing pages in this TLB cache and it depends a lot on the hit ratio (The ...
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Why windows 11 does not support old cpu?

I know CPUs execute machine language code. Also I know operating systems such as Windows and Linux are a piece of code. But I cannot understand why Windows 11 does not run on a somewhat old CPU. Can ...
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what is the relation between operating systems and automata theory?

I want to do some research on how machine theory (automata theory) is applied in the operating system. Also thank you for introducing useful links and books.
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Virtual and physical address spaces in address binding

I just need to check my understanding regrading two points .As was stated in the textbook "Operating systems concept " : The compile-time and load-time address-binding methods generate ...
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Does every thread store its context in a separate PCB?

Is a thread's context stored in the process's PCB, or is a new PCB created for the thread?
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More info about traffic controller in process management of an OS

I was going through some texts and shared PPT of my university and I found the term "traffic controller" in the Process management section under the functions of an Operating System. The PPT ...
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Understanding the difference between API, system call and system call interface

as anticipated in the title, I can't understand the difference between API, system call and system call interface. Most of all, I can't understand if the system call interface is actually a "...
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Boot Loaders, Boot Sectors, BIOS, and GRUB

Again, I must apologize if this is "easily googlable". I have tried. My understanding is that the BIOS typically looks for the magic number 0x55aa at the end of a 512 byte sector (so bytes #...
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How are I/O operations handled on a computer?

What does the computer do when an I/O operation needs to be done during the process? Does the message that we need to do some I/O operation directly reaches the device controller or device driver? ...
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Tigers and elephants can't drink water from a pond simultaneously, while more than one tiger or more than one elephants can drink water simultaneously

Below is a question on synchronization mechanism which was asked in an interview in Indian Statistical Institute, M.Tech CS. I got hold of it from here. There is a forest where there are tigers and ...
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Can spooling be used for all I/O devices?

I read in my textbook that a spooling could be used to elinmate the possibility of.having a deadlock in some cases. But does spooling work for all I/O devices? If not what are some examples of those ...
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How MAC (Mandatory Access Control) model prevents trojan horse attacks?

I've heard that the MAC Model prevents Trojans to charm files on the system. How is it possible? Can somebody show any example that MAC model protects us against it?
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Why is C still the fastest? Critique my take

A friend and I were surprised that C still has near-best performance among languages. I thought about why this is, and I wrote up a few paragraphs. I wonder if the friendly folks on CS stack could ...
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What does it exactly mean by information management as a function of O/s

I have read that information management is a function of O/s by which it A) Manages, stores, retrieves,modify data. It makes sure that right people have access to their information. B) Some of the ...
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How to study in and outs ofOperaring Systems

I want to study operating systems in depth, in particular windows, linux and android OS. What is the best way to get started?
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Is there an OS with capability to freeze/unfreeze any app?

I'm looking for an operating system (commercial opensorce or any) which can freeze any currently running application (video/audio playback, a game etc.). While the app is frozen the OS must be able to ...
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Definition of the term "access efficiency" in the context of computer systems

In a two-level virtual memory, the memory access time for main memory, $t_M=10^{−8}$ sec, and the memory access time for the secondary memory, $t_D=10^{−3}$ sec. What must be the hit ratio, $H$ such ...
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Are there any operating systems that utilize only user threads?

We're going over threading models in my freshman CS class. Are there any examples of operating systems that use exclusively user threads (N:1)? It looks like 1:1 is far and away the most common model ...
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Choice of process to swap out to reduce thrashing

Is the problem to decide which process should be swapped out in the event of thrashing, a NP problem? Are there any heuristics to decide a suitable candidate(like the largest process or one which has ...
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Question Regarding number of frames required for multilevel page tables

I have a problem and I'm not sure where I am going wrong with this, description so as you can see it is given a 3 level paging system with 8 bit page index on every level, now I break down logical ...
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Context switching and Program Counters

This is a really short question and a straightforward one for anyone who knows the subject well. But its also super specific, so I can't find the answer online. I know a program counter is saved when ...
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Exceeding limits of virtual address space

I still am confused whether I am asking the right question but here goes Consider a X bit processor. It can address theoretically a main memory of 2^x bytes(assuming byte addressable). Now consider an ...
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Can Operating system allocate a page of process to any free frame in memory?

Consider I have a user program of 6 pages and 4 byte page size. Now my memory has 300 frames out of which 10 frames are free for allocation. Can the OS allocate page 1 of the given process to any of ...
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Why does python's threading library use OS level threads when it can't achieve parallelism?

I was surprised to hear that the threading module from python uses OS level threads. From what I know, OS level threads are more expensive (but can achieve parallelism) meanwhile green threads are ...
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Why is copy speed periodic? (or seems to be)

When copying ~80Gb data from one USB 3.2 stick to another, i noticed that the GUI of the transfer speed had clear periodicity. Out of curiosity, what could be the reason for this? No other active ...
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