I think most people familiar with the original Xbox hw (like people working on xemu :)) take offense when you say it's just a PC. It's PC hardware, but nothing much is shared with the "IBM PC" architecture-wise. Even the software side is very different. It's not running a customized version of Windows, but the Windows kernel. One stripped down to 256kb, including the boot up animation and sound. That design for example required that a lot of things get linked into a game's executable, like network drivers and the entire TCP/IP stack.

If it were that easy, we'd have had a wine pendant for Xbox binaries 20 years ago. Cxbx is pretty much the wine approach to Xbox emulation and it's far from perfect.

There are two major original Xbox emulators - cxbx/cxbx-reloaded, which originally tried to do both LLE and HLE but these days does exclusively high-level emulation like you are describing, and xemu (this one), which does mostly low-level emulation.

So no, in this case Xemu runs the original Xbox kernel. This is why it's more compatible and generally much more robust than cxbx in terms of game support.

There are a lot of challenges with doing HLE for Xbox. While there is a kernel, its HAL is very low-level. Games are statically linked against the entire stack of DLLs that you'd usually find in Windows (the Xbox SDK), and depending on when they were released, can have one of about a gazillion versions of the Xbox SDK in them. So doing HLE is a matter of finding and hooking an enormous number of SDK functions, but also keeping up with the plethora of minor changes which were made constantly through the life of the console. Emulating the kernel doesn't get you very far, because it still provides low-level interfaces to (for example) manipulating GPU state, so you end up having to implement the GPU hardware in LLE anyway.

Per the documentation you have to provide dumps of the original Xbox bootroms, and it can optionally use a HDD image taken from a real Xbox, but the latter isn't required because they provide a basic cleanroom reimplementation of the dashboard you can use instead.

https://xemu.app/docs/required-files/

The CPU in the Xbox was literally an off-the-shelf Intel processor (some crazy people even soldered in faster CPUs that were never meant for the Xbox) but as I understand it the GPU is weird, and that's where most of the difficulty with emulation comes from. It's a unique mashup of GeForce 2 and GeForce 3 IP that was never used anywhere else, so the existing efforts to reverse engineer GF2 and GF3 for Linux drivers were of limited use.

This is a myth that is incorrect. The original Xbox's BIOS bares little to no resemblance to Windows 2000 (its closest contemporary) and runs from a 1MB flash chip at most. Games run Bare Metal on the system

The Xbox hardware was also quite advanced for its release date (2001). Many PCs at the time still had 100MHz FSB but the Xbox ran at 133MHz. The Xbox also had DDR RAM, not much of it (64MB), but DDR wouldn't be commonplace until the Pentium 4 and Athlon XP platforms a couple years later. Most PCs were still running regular single-channel SDRAM.

I've built a near-period correct PC with a later and faster CPU (Tualatin at 1.0GHz vs Xbox's Coppermine at 700MHz), more RAM (512MB), faster GPU (GF4 Ti4400), but it still can't achieve the raw memory and GPU bandwidth the Xbox had.

If I remember right, most of the "operating system" was linked statically into the game images (AFAIK at least the DirectX libs, not sure about any low level "firmware" stuff). I'm pretty sure there was no concept of "hardware drivers" though.

If I am not wrong this is a LLE (low level emulator) rather than a hle so it should emulate the hardware rather than the kernel. So you need the dump of the microsoft's xbox kernel for it to work