I wanted to create a similar "from scratch" installation by adding the bootloader and the kernel to a virtual disk image, then connecting the kernel-mode debugg

I wanted to create a similar "from scratch" installation by adding the bootloader and the kernel to a virtual disk image, then connecting the kernel-mode debugger from the Driver Kit to a virtual machine COM port, and checking what files the kernel expects to see before it falls over (as it doesn't find them). My end goal would have been to add MSYS2 and launch an init system and ultimately a terminal. Unfortunately there were a lot of steps before the system gets to a usable state, I don't think I was anywhere near that point even after a whole lot of reboots & debug sessions. The summary in this Wikipedia article about the startup process helped a lot: https://en.wikipedia.org/wiki/Windows_NT_startup_process https://en.wikipedia.org/wiki/Windows_NT_startup_process