Due to different requirements imposed by Linux and Windows on the implementation of checksum offloading, Windows Server 2003 guests running with para-virtualized drivers previously experienced many TCP retransmissions and showed poor network performance. With this update, checksum offloading has been disabled in the drivers and TCP sessions on Windows Server 2003 guests no longer exhibit problematic behavior.
Previously, the para-virtualized Xen network driver did not report when it consumed packets. As a result, when using traffic control on virtual networks, Windows virtual machines dropped packets. Now, the driver correctly implements the "rx-notify" feature, packet consumption is reported promptly to the network back end running on domain 0, and traffic control does not cause unexpected packet drops.
Para-virtualized Xen drives did not handle properly the "MODE SENSE" command. Consequently, Windows guests failed to initialize a mirror or a striped dynamic volume that included a para-virtualized Xen drive, leaving the volume in a failed state. With this update, the "MODE SENSE" command implementation has been fixed and dynamic volumes now work properly with para-virtualized Xen drives.
A variable was not reset to NULL when Windows XP sent a ScsiStopAdapter control message to the RHELSCSI driver. Consequently, when running the debug version of the drivers on Windows XP, an assertion failure was reported during hibernation. Now, the stored device extension is reset to NULL when the adapter is stopped and the assertion failure no longer occurs.
Previously, Windows guests did not acknowledge the "xm shutdown -H" command run from a host. Consequently, attempting to turn off a Windows virtual machine with "xm shutdown -H" failed. Furthermore, it prevented "xm shutdown" from working until the virtual machine was rebooted. Now, the para-virtualized Xen network driver triggers a shutdown of a virtual machine when "xm shutdown -H" is sent, thus fixing this bug.
Due to different requirements imposed by Linux and Windows on the implementation of checksum offloading, Windows guests running with para-virtualized drivers were unable to communicate with other guests running on the same host. With this update, checksum offloading has been disabled in the drivers and communication between Windows guests running on the same host now works correctly.
Para-virtualized Xen drives did not handle properly the "READ CAPACITY(16)" command. Consequently, the "SCSI compliance test" in the Windows Logo Kit failed. Now, the "READ CAPACITY(16)" command implementation has been fixed and the compliance tests for it no longer fail.
Note that this bug does not cause any known problem in normal operation.