C Interview Questions for Device Driver Developers

1. BSS & Data section---> By default compiler Initialize the STATIC Variable na, why not the static variable stores in data section ? why it stores in BSS?
2. Where the EXTERN VARIABLE stores in the memory layout ( program memory layout ).
3. SWITCH CASE statement ---> which searching tech is internally follows
4. I have a mutx & semaphores & spin lock . When to use sem's & when to use mutex, & when to use spin locks?
5. I have BH tech's ----> softirq , tasklets , work queues -----> which tech we use & where we use it?
6. Is it possible to use static variable in the HEADER FILE / LIBRARY