Satoriwas the original project name for the first XenSource / Microsoft project under which we delivered  components to Microsoft (for free download for use with Windows Server 2008 Hyper-V)to enable Xen-ready Linux guest OSes to run with optimal performance on the Hyper-V hypervisor.  This involved developing an adapter that ensured that what we call paravirtualized(and Microsoft calls enlightened) Xen VMs could interface directly to the hypercall API of the Hyper-V hypervisor and run with optimal performance, while respecting the need for a clear line of separation between GPL and proprietary code bases.   

In addition to the Satori hypercall adapter Satori delivered  enlightened disk (StorVSC) and network (NetVSC) drivers for Xen-enabled Linux guests on Hyper-V, that interface directly to the I/O Virtualization Stack in the Parent Partition of the hypervisor via the VMBus ABI.  This optimizes virtualized I/O for high performance and removes the need for emulation of legacy hardware.  Hyper-V VMs are completely compatible with the now free XenServer virtual infrastructure platformas a result of our close attention to driver and virtual hardware compatibility with Microsoft.

We are now adding an enlightened mouse driver (InputVSC) to offer major usability enhancements for Linux guests on Hyper-V.   The reason for the delay in releasing this driver is that it requires interaction with part of the USB framework in Linux, for which no GPL exports are available. To workaround this limitation the InputVSC driver code is based on a back-port of the HID driver used in upstream versions of Linux which does have GPL exports.  Code linked with the back-ported HID driver also needs to be released as GPL v2, which is what xen.org has now done. You can download the InputVSC driver for Linux guests for Hyper-Vhere.   (the enlightened mouse comes from [here|http://www.childrensillustrators.com/illustratorDetails.cgi/32627])