Building an OS - Protected mode: how your OS can protect itself

In depth explanation of what x86 protected mode is, how it works, and how to switch to this mode. Links: - Patreon: https://www.patreon.com/nanobyte - Discord channel: https://discord.gg/RgHc5XrCEw - Source code: https://github.com/chibicitiberiu/nanobyte_experiments/tree/master/ProtectedMode - Bochs config file: https://github.com/chibicitiberiu/nanobyte_os/blob/master/bochs_config Documentation: - Protected mode (wikipedia): https://en.wikipedia.org/wiki/Protected_mode - Protected mode (osdev): https://wiki.osdev.org/Protected_Mode - Intel manual: https://software.intel.com/content/www/us/en/develop/articles/intel-sdm.html - NMI interrupts: https://wiki.osdev.org/Non_Maskable_Interrupt - GDT: https://wiki.osdev.org/GDT - Printing to the screen: https://wiki.osdev.org/Printing_To_Screen Chapters: 0:00 Intro 0:37 History of x86 8:17 What is protected mode 8:57 Privilege levels 10:39 Segmentation 11:36 Paging 13:24 Switching from real to protected mode 17:36 A20 gate 23:38 GDT 27:26 Finishing the switch 33:18 Printing text from protected mode 36:46 Switching back to real mode 40:02 Conclusion