https://www.stormshield.com/news/how-to-run-userland-code-from-the-kernel-on-windows/
Before Windows NT 4.0, the graphical part of the Windows subsystem was implemented completely in userland. Starting from NT 4.0 Microsoft decided to move a large part of the Window Manager and the Graphics Device Interface to kernel-mode in the Win32k.sys component. However, part of...