Saw this on their page:

"Unlike the NT™, system does not feature a separate Hardware Abstraction Layer (HAL) between the physical hardware and the rest of the OS. Instead, XT architecture integrates a hardware specific code with the kernel. The user mode is made up of subsystems and it has been designed to run applications written for many different types of operating systems. This allows us to implement any environment subsystem to support applications that are strictly written to the corresponding standard (eg. DOS, or POSIX)."

It's a little hard to follow, but I'm thinking more monolithic kernel than "hybrid"?

Modern NT builds haven't really been using the HAL the same way either. It's been a pain because windows on arm kernels have been pretty tied to Qualcomm hardware so far.

This is an ARM issue, not a Windows one. Same reason Linux needs device tree overlays.

HAL.dll was intended to solve the exact same problem as device trees. That's why there's custom HAL.dlls for weird x86 but not PC platforms like some of the SGI boxes. Stuff like sure, it's the same processor arch, but the interrupt controllers, system bus, etc are completely different and not introspectable via normal PC mechanisms.

The issue is that WoA kernels have moved away from heavily embracing hal.dll, instead inlining a lot of functions into the kernel that used to be hal.dll functions for perf reasons. If they kept the original architecture it would have been easy, but they've changed it fairly recently to be less portable.

"Instead, XT architecture integrates a hardware specific code with the kernel."

Isn't this a bad idea?

I'm not taking with authority here, but isn't Linux doing it like that, too?

When you're compiling the kernel you're able to toggle various hardware flags to add to the compilation.

And AMD graphics cards generally work better then NVIDIA (on Linux) because the official drivers have been upstreamed vs Nvidias that haven't

Sounds like you know more about it than I do!