GenAHCI is storage driver replacement for Windows XP, Vista, 7, 8.0 and their Server equivalents based on official Windows 8.1 StorAHCI source code sample. https://github.com/microsoftarchive/msdn-code-gallery-microsoft/tree/master/Official%20Windows%20Driver%20Kit%20Sample/Windows%20Driver%20Kit%20(WDK)%208.1%20Samples/%5BC%2B%2B%5D-windows-driver-kit-81-cpp/WDK%208.1%20C%2B%2B%20Samples/StorAhci%20StorPort%20Miniport%20Driver/C%2B%2B
This patched source code is based on previously developed patch for Windows 8.0 source code sample by Kai Schtrom https://sourceforge.net/projects/storahci-for-windows-2003/
Even it looks like Windows 8.0 to 8.1 is small step, driver code was changed on many places. Almost everything was patched to be compatible with Windows XP and driver can be succesfully installed or integrated into Windows Setup