My introduction to this was the 'Direct Execution' chapter of the book 'Operating Systems: Three Easy Pieces'. It's a fantastic write up on not just how system

My introduction to this was the 'Direct Execution' chapter of the book 'Operating Systems: Three Easy Pieces'. It's a fantastic write up on not just how system calls work, but the motivation behind why operating systems even implement them in the first place. It's not specifically about Linux, but the book is clearly heavily inspired by early *nix designs and it's still applicable. You can read it for free here: https://pages.cs.wisc.edu/~remzi/OSTEP/cpu-mechanisms.pdf https://pages.cs.wisc.edu/~remzi/OSTEP/cpu-mechanisms.pdf