Depends entirely on the professor. Some professors develop their own textbooks and release them for free. https://pages.cs.wisc.edu/~remzi/OSTEP/ https://pages

Depends entirely on the professor. Some professors develop their own textbooks and release them for free. https://pages.cs.wisc.edu/~remzi/OSTEP/ https://pages.cs.wisc.edu/~remzi/OSTEP/