Run Xbox Games on ReactOS

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Notice: This page is about FOSS implementation of the gaming kernel based on ReactOS for original Xbox. For the full port of ReactOS desktop operating system see Xbox Port.

ReactOS has an original Xbox port but it can run only Windows applications and lacks ability to run actual original Xbox games.

A new non-Desktop ReactOS kernel target must be created for running Xbox games. It would be specificly meant to run on Xbox hardware, and would have to support Xbox kernel functionality.

Specifically, the XBE loading must be implemented but probably also various other tasks related to memory management and more.

Problems

Xbox OS uses a radically different software architecture from Windows:

  • Xbox Executables (XBE) are used instead of Executable (EXE) files.
  • XBE run in ring 0 and no ring 3 exists. This may require some changes to ReactOS.
  • XBE expect to locate HAL and other kernel API functions in a single statically linked kernel.
  • XBE are also statically linked.
  • XBE access hardware directly, so support can only be provided for ReactOS running on an original Xbox.
  • The kernel uses cryptography and stores keys to encrypt various data (network traffic, saved games, etc.), these keys must be dumped, and key derivation must be recreated.
  • The kernel only provides some critical hardware support (mostly video Encoder and IDE controller).

These changes mean that a custom desktop-less OS variant of ReactOS, specifically for original Xbox, has to be made.

This variant would be equivalent to the original xboxkrnl.exe by Microsoft. It would be binary-compatible with original Xbox games (but incompatible with non-Xbox hardware and Windows applications).

Related projects

XQEMU

XQEMU is an original Xbox emulator that emulates the hardware level, specifically Xbox revision 1.0. XQEMU is targeting computers running Linux, Mac OS X and Windows.

Because it emulates hardware, it requires ROM images (some of which are hard to obtain) to be able to boot.

The code in XQEMU can be used to understand some of the hardware, which will have to be supported by ReactOS.

Additionally, XQEMU could possibly be used to test ReactOS. However, this might not work correctly, as XQEMU only supports hardware access methods as used by Microsoft's original kernel. Some legacy devices or device access methods might not be supported (PIO vs. DMA, for example).

Cxbx-Reloaded

Cxbx-Reloaded is an original Xbox emulator that emulates the kernel level. It also hooks into the game code (by using a pattern-search) to avoid direct hardware access.

As Cxbx-Reloaded is targeting computers running Windows, most of the kernel re-implementation are simple adapters to Windows functions; however, the implemented variants are confirmed to work with some original Xbox games.

Other kernel functionality is implicitly documented in code and might be useful (such as key derivation on XBE load).

Since Cxbx-Reloaded uses very specific hardware emulation ways, it can't be used to emulate a virtual Xbox for testing ReactOS.

Related articles

See Also