In another sign interoperability between virtual Linux and Windows operating systems is gathering pace, Red Hat has quietly released a set of drivers to improve the performance of Windows guests hosted on Linux's Kernel-based Virtual Machine (KVM) hypervisor.

The netkvm driver is a Network Driver Interface Specification (NDIS) miniport network driver for Windows guests and viostor is a Storport miniport driver, also for Windows guests.

Windows Server 2003 and later operating systems support Storport, a storage port driver that is suitable for use with high-performance buses, such as fibre channel buses and RAID adapters, according to Microsoft.

The Storport driver offers better performance than the standard SCSI Port driver and “addresses the needs of high-end storage vendors”.

The KVM project has added a page to its Web site detailing the new Windows guest drivers.

Commenting about the new drivers on his KVM blog, Haydn Solomon said the release of paravirtual drivers for Windows under the GPLv2 license “took some time in coming”.

“To date only paravirtual network drivers were published but this release includes paravirtual block drivers for Windows which is very interesting,” Solomon wrote.

According to Solomon, paravirtual block drivers for Windows has been “very low key and known to be unstable”.

“With Redhat expecting to release it’s Enterprise 5.4 version in September, maybe they’ve got windows paravirtual block drivers in working order?”

The release comes a month after Microsoft stunned the open source community by releasing its own set of virtualisation drivers for the Linux kernel under the GPL.

Microsoft's LinuxIC (Integration Component) drivers are designed to improve the performance and usability of Linux guests running on Windows servers.

Microsoft's Port 25 open source community blog has technical details about the LinuxIC drivers.

Microsoft has also pledged interoperability with the open source Xen hypervisor which is backed by Citrix and Novell.

The KVM project is online at www.linux-kvm.org.