The process was good, HR was also very friendly and positive

The technical interview experience was poor.

Initial 2 interview round went very well and answered all C, Linux, Kernel, DS answers.

In 3rd round of interview : Even though I have not written anything related to memory management work and its design in my CV, the interviewer has spent almost an hour on the same topic even after I have refused several times not to have much idea on that, It was just a time pass of an hour interview, also the questions were mostly on memory design.

In 4th round immediately after 3rd one: C++ basic questions, that I had answered well, but the interviewer was expecting me to have advance knowledge on it(again I have wrote basic of c++ in my resume clearly).

They might be asking based on their position requirement c++ & memory management related requirement but resume screening should have done properly if they had strick requirement instead of wasting 4-5hrs of time(telephonic + 4hrs interview).

C Programming

C++ Programming

Linux System Programming, Kernel, Driver & some SoC level questions

Program writing based on C