Interview Questions on RTOS


Hi folks, RTOS is a tricky thing to handle, it does not provide full functionality of a General Operating Systems but still it gives functionalities without loading MCU much. I piled up interview questions on RTOS, few questions may be even in context of LINUX. A good hands-on with RTOS will enhance in understanding its behaviour and usability. Each RTOS in market has its own set of pros and cons, they also provide some configurability parameters by changing which we can do some functionality changes as per application requirement. I am familiar with ThreadX and freeRTOS. If you have any queries better post a comment, I will comeback with information which I can. You may face below questions when applied for embedded related positions with companies such as Qualcomm, Broadcom, securify, moschip, Global Edge, Aricents, Mirafa, Graphene, Mojo Networks, Lantronix, Adtran, Votary Softech etc.

  1. What is a Task/Thread
  2. What is a process ?
  3. Diff between Thread and Process ?
  4. Diff between Hard and Soft RTOS ?
  5. Diff between GPOS and RTOS ?
  6. Shceduling mechanisms in RTOS ?
  7. Does threads in RTOS provide virtual memory ?
  8. Does RTOS protect one threads memory from other ?
  9. Where is thread usage feasible, where would process be feasible ?
  10. How will threads communicate ?
  11. Can two threads call the same function at one instance ?
  12. What happens when a RTOS with time slice based scheduling have two threads with while(1) in it ?
  13. What is Semaphore and where can it be used for ?
  14. What is Mutex ? Where it suits better ?
  15. Diff between binary Semaphore and Mutex ?
  16. Diff between Semaphore and Mutex ?
  17. How can you implement Mutex using Semaphore ?
  18. How will OS talk to Threads and Processes ?
  19. What all parameters are configurable to create a Thread ?
  20. What happens when a Thread Exits ?
  21. How can you synchronize between two threads ?
  22. How can you synchronize between two process ?
  23. Can one process call functions of other process ?
  24. What is Priority Inversion ? Is it a problem or a feature ?
  25. What can be done to surpass  priority Inversion ? explain with an example
  26. What is Priority Inheritance ? What the benefit you get out if using it ?
  27. What is Priority Ceiling ?   What the benefit you get out if using it?
  28. How can you detect Memory/Buffer corruptions ?
  29. What is spinlock, benefits using it ?
  30. What is dead lock ? How can you avoid dead lock ?
  31. What are IPC available in Linux and how they are different from one other ?
  32. What are Message Queues, how will a thread waiting on a Q will be invoked when there is a message on that Q ?
  33. What is Context Switch ? what all happens at context switch ?
  34.  What are signals ?  Can a thread wait on signals ?
  35. Can you use Semaphore/ Mutex in ISR ?
  36. Can two threads use same address 0x100 at same time ? If so how is it possible ?
  37. What is fastest IPC and why ?
  38. What are sections shared by threads in Linux ?
  39. How are driver threads diff from general threads in RTOS ?
  40. What happens when ISR and DSR functions are accesing same buffers ?
  41. What are the criteria which help in choosing a RTOS?
  42. How can you implement a mutex using a semaphore?
  43. Does RTOS support kernel mode and user mode functionality?
  44. What are the benefits of having user mode and kernel mode?
  45. What can be a requirements for a minimal micro OS ?
  46. What are all the issues which come up using multiple threads in a application?
  47. Why and when memory protection is used and required in a RTOS?
  48. How is protection achieved by an RTOS?
  49. What are all IPC mechanisms available in general RTOS?
  50. ….Will add many more Soon….
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