Qualcomm (Linux Team):
1st Round:
1) You are given two 32-bit numbers M and N, and two bit positions I and j. Write a function to insert M into N at I and assume that the space j-I can compass all the required bits of M
2) You are given a function read(int blockNo, void *buf) - returns a 512 byte block. read_offset_size(int offset, int size, void *buf) - implement this function using the above prototype
2nd round:
DMA, Semaphore & mutex(Differences), Interrupts, what type of issues you have faced in your project how did u solve them, Device driver how to allocate a new device procedure for that, what is priority inversion and priority inheritance. Do u know about jtag?
What debbugin tools you have used to debug the issues.
1) Rotate an array for the given number of times....
3 4 5 1 2 -->original array
1 2 3 4 5 -->rotated 2 times
2) Given an unsigned 32 bit integer, count the numer of occurrences of pattern 10 .....(Write program using bitwise operations only)
1000 --> 1 time
101011001-->3 times
3rd Round:
All OS concepts:
What are different scheduling algorithms?
What are synchronization techniques?
Difference between Mutex and Semaphores?
What is Deadlock?
What is fragmentation in OS?
What are pages in memory management? What is page fault when does it occur?
What is Interrupt?
What is cache memory, use of Virtual keyword, difference b/w process & Thread, what is fork, vfork. how fork is used, DMA(how controller works). RTOS some basic questions, Watchdog timer and how it is usefull. Why we use timers. Any bus protocols u have used.
What is the need of synchronizing mechanism such as Semaphore and Mutex? And why do we need OS support for implementing these two.
Puzzle: 25horses find minimum number of races to determine 1st, 2nd and 3rd place. Answer: 7