Linux Interview Questions

       1.      What is Kernel-Level Threads?
2.      What is a kernel space and user space?
3.      What is SELinux?
4.      What is kernel updation?
5.      What is shared memory?
6.      What is the use of shared memory?
7.      Can you access a C library function from kernel space?
8.      Explain difference between modular & monolithic kernel.
9.      Explain kernel compilation steps.
10.  Explain semaphore settings.
11.  How Does Linux Kernel Versioning Work?
12.  Explain booting process of Linux.
13.  What is the difference between soft & hard links?
14.  Which file stores kernel configuration details?
15.  How to check the currently configured kernel parameters on a Linux server?
16.  Can you access a kernel function from user space? Justify.
17.  How the device drivers are broadly classified?
18.  How do you register a character device in the kernel?
19.  How are character, block, network devices identified in the kernel?
20.  Does Linux Support USB Devices?
21.  What is a system call?
22.  What is User Label Thread?
23.  How do you register an interrupt handler for any device from with in your driver? 
24.  What is a proc file system?
25.  What is the difference between sysfs filesystem and procfs file system?
26.  Have you heard of the term VFS? What is its purpose in the kernel?
27.  What are the major differences between 2.4 kernel and 2.6 kernel?
28.  Describe the basic structure of any kernel module.
29.  How do you insert and remove a kernel module? Explain the flow?
30.  What are wait queues? How are they used?
31.  How many wait queues does the kernel have?
32.  How many run queues does the kernel have?
33.  Did you hear about a term called jiffies? What is its significance in the kernel?
34.  How would you set up a function in the kernel to be invoked periodically every one second?
35.  How would you achieve synchronization in the kernel?
36.  What are the various locking mechanisms in the kernel?
37.  When would you use a spin lock and when would you use a semaphore?
38.  What are bottom halves? List out the available variants of it and explain the usage scenario of each.
39.  What would you do to register an interrupt line shared by two or more devices? How does the kernel handle this scenario?
40.  What is a process context and what is an interrupt context?
41.  When does the scheduler get invoked?
42.  What is preemption? Why is 2.6 kernel called fully preemptive?
43.  What are the available scheduling algorithms in kernel?
44.  Why 2.6 kernel scheduler called an O1 scheduler?
45.  Can you access any kernel function from the interrupt handler?
46.  Will there be any network device file in your root file system’s /dev directory?
47.  How is a network device accessed from the user space?
48.  What is the kernel timer tick rate? Can this be altered? If so how? What is the effect of altering this?
49.  What is a kernel Oops? When does it occur?
50.  What is a kernel panic? When does it occur?
51.  What is a kernel thread? How would you create it from a kernel module?
52.   How would you invoke a user space program from within the kernel space?
53.  How does the kernel handle the delivery of signals to processes? When are the signals delivered?
54.  What makes an OS an RTOS?
55.  What is a PCB (process control block)? What is its significance in the kernel?
56.  How do you access the PCB of the current process?
57.  What is a ram disk?  How would you set up your kernel to use this?
58.  Can you briefly explain the kernel boot up sequence?
59.  What happens if kernel is unable to mount any root file system?
60.  What is the first user space process to be executed after kernel boot up?
61.  How do you allocate memory in a kernel?
62.  What is the difference between physical address, kernel virtual address, and user virtual address?
63.  How do you debug a kernel module?
64.  How do you setup KGDB for kernel module source level debugging?
65.  Is there any memory level debugging tool for kernel? How did you use it?
66.  What is trace tool and gstreamer in Linux?
67.  What are semaphores? Differentiate mutex, binary semaphores and counting semaphores?
68.  Explain Round robin scheduling and its disadvantage? Quantum time in round-robin scheduling algorithm?
69.  Explain SJF algorithm?
70.  IS Linux is RTOS or not?
71.  Booting process of Linux kernel in target.
72.  Explain paging in Linux? What is memory protection in Linux?
73.  Explain Linux hash tables for c.
74.  Explain Top Halfs & Bottom Halfs in Linux
75.  What text filter can you use to display a binary file in octal numbers?
76.  Which commands are used to set a processor-intensive job to use less CPU time?
77.  Brief about the initial process sequence while the system boots up.
78.  What is the linux distribution version, you have developed driver module and what is the current version of that distribution.
79.  Drawn figure of three systems A,B,C are connected in network and IP addresses  are shown. Check the ip configurations are correct?
80.  If three ethernet cards are present in the system, how will you configure, every boot, each ethernet cards to get the same ip address.
81.  What is Virtual file system?
82.  What is AT command and tell some commands?
83.  Write the flow of system calls in socket for tcp and udp.
84.  Which call will block in tcp socket flow?
85.  Explain steps of compiling linux kernel and booting.
86.  What are the flavors of tcp/ip?
87.  Explain the Virtual Memory, Paging and Swapping concepts in Linux.
88.  What are the different IPCs in Linux.
89.  Explain socket programming in Linux.
90.  How two processes will communicate with each other? IPC concepts what are IPC APIs in Linux?
91.  Explain paging in Linux? What is memory protection in Linux?
92.  What are the differences between the OS (LINUX, SYMBIAN)?

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