January 30, 2015
Table of Contents Introduction Page 3 Terminology Page 4 General Limits and Expectations for Graphics and Monitor Support Page 5 Graphics Processor (GPU) Support Page 6 Specialized Monitor Types Page 7 Multi-Monitor Support Page 8 Haswell Docking Stations Page 9 Dual-Monitor Testing Notes for Selected Docking Stations Page 10 3D Graphics in XenClient VMs with Intel GVT Page 11 3D Graphics in XenClient VMs Page 12 Simplified Intel VGT Architecture Page 13 Graphics Aperture BIOS Settings Page 14 Intel GVT Resources Page 15 Graphics Drivers in XenClient VMs and Synchronizer Graphics Policy Settings Page 16 Graphics Drivers for XenClient VMs Page 17 Graphics Drivers in Windows Device Manager Page 18 Synchronizer Policy Settings for Graphics Page 19 Synchronizer Policy Details Page 20 Which Graphics Driver Will Be Installed in the VM? Page 21 Page 2
Introduction Summary This document provides some notes on how XenClient Enterprise supports various video and monitor components, use cases, and modes of operation. Applicability This document is applicable to XenClient Enterprise version 5.5.1. Portions of this document may not be applicable to earlier or later versions of XenClient Enterprise. Each XenClient deployment is unique and the information presented in this document may lack context or consideration of specific environments or use cases. Any changes or processes that may be suggested by this document should be thoroughly tested before being applied to production systems. Disclaimer Any sample code, scripts, SQL queries, commands, or other such information (hereafter referred to as code ) presented in this document is provided to you AS IS with no representations, warranties or conditions of any kind. You may use, modify and distribute it at your own risk. CITRIX DISCLAIMS ALL WARRANTIES WHATSOEVER, EXPRESS, IMPLIED, WRITTEN, ORAL OR STATUTORY, INCLUDING WITHOUT LIMITATION WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NONINFRINGEMENT. Without limiting the generality of the foregoing, you acknowledge and agree that (a) the sample code may exhibit errors, design flaws or other problems, possibly resulting in loss of data or damage to property; (b) it may not be possible to make the sample code fully functional; and (c) Citrix may, without notice or liability to you, cease to make available the current version and/or any future versions of the sample code. In no event should the code be used to support of ultra-hazardous activities, including but not limited to life support or blasting activities. NEITHER CITRIX NOR ITS AFFILIATES OR AGENTS WILL BE LIABLE, UNDER BREACH OF CONTRACT OR ANY OTHER THEORY OF LIABILITY, FOR ANY DAMAGES WHATSOEVER ARISING FROM USE OF THE SAMPLE CODE, INCLUDING WITHOUT LIMITATION DIRECT, SPECIAL, INCIDENTAL, PUNITIVE, CONSEQUENTIAL OR OTHER DAMAGES, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. Although the copyright in the code belongs to Citrix, any distribution of the code should include only your own standard copyright attribution, and not that of Citrix. You agree to indemnify and defend Citrix against any and all claims arising from your use, modification or distribution of the code. Page 3
Terminology Haswell Processor Refers to intel 4th Generation Core CPUs. Example: Core i5-4200u (a common Haswell processor for laptops). Haswell Platform A computer with a Haswell processor and support for Haswell features enabled in the BIOS. Examples: Dell Latitude E7440, Lenovo ThinkPad T440, HP EliteBook 1040-G1. GVT Intel Graphics Virtualization Technology. Provides hardware-assisted virtualization of the Intel integrated graphics processor. Only available for Haswell processors with integrated Intel graphics (no NVidia or AMD graphics). GVT VM A XenClient VM running on a Haswell platform utilizing GVT graphics. A GVT VM will have the native Intel graphics driver installed and have direct access to the GPU. Although the hypervisor (Xen) plays a role in mediating access to the GPU. XPDM Legacy graphics driver architecture introduced by Microsoft for Windows XP. Non-GVT Windows 7 VMs will use a para-virtualized XPDM driver by default (with no 3D rendering). WDDM Graphics driver architecture introduced by Microsoft for Windows Vista and carried forward to Windows 7 and Windows 8. There are three different WDDM drivers available for XenClient VMs: GVT VMs will use the native Intel driver, which is a WDDM driver. Non-GVT Windows 8 VMs will use a para-virtualized WDDM driver with the built-in Microsoft 3D software rendering library. Non-GVT Windows 7 VMs may also use a para-virtualized WDDM driver with an external 3D software rendering library. Page 4
General Limits and Expectations for Graphics and Monitor Support
Graphics Processor (GPU) Support Intel Integrated Graphics Generally supported and recommended for XenClient computers. Haswell (4 th Generation Core): Supported and required for GVT VMs. IvyBridge (3 rd Generation Core): Also supported, but not for GVT VMs. SandyBridge (2 nd Generation Core): Generally supported, but not for GVT VMs, and some Core i3 CPUs may have issues. Earlier Generations: Not actively tested or supported but many will still work. Non-Intel Graphics (AMD / NVidia) Generally untested and unsupported. Some AMD/NVidia GPUs may work with limitations. Particularly problematic: AMD Quadro GPUs. NVidia Optimus technology (even if disabled in the BIOS). Encrypted computers with non-intel graphics may boot into a black screen. If the encryption unlock password is entered at the black screen, the computer may boot normally. This appears to be improved in XenClient version 5.5, compared to previous versions. Page 6
Specialized Monitor Types Pivoting Monitors Not supported. Will generally work in landscape mode. But when pivoted to portrait mode, the graphics will not adjust. USB Video Display Devices Not supported. It may be possible to pass the device through to a Windows VM. If a suitable driver is available, it may get installed as a Windows device. But the device may or may not work as expected within the VM. KVM (Keyboard/Video/Mouse) Devices In theory, KVM devices should just work with XenClient (and some do). In practice, some KVM devices may introduce issues such as: Video not displaying properly (black screen). Video instability or flickering. Incorrect resolution. These issues are often caused by the KVM not passing along configuration information for the monitor in the way expected by XenClient. There can also be issues with XenClient running in headless mode (no monitor attached). In particular, VNC access to the Engine may not work properly. Page 7
Multi-Monitor Support General expectations for multi-monitor support, based on platform type. Results may vary between specific laptop and docking station models. Desktop Computers One or two monitors connected to different ports on a single GPU. No support for multiple GPUs. All-In-One Computers Integrated screen, plus one external monitor. Laptop Computer (Undocked) Integrated screen, plus one external monitor. Or two external monitors, in which case the integrated screen is not active. Laptop Computer (Docked) One external monitor connected to the docking station generally works. If the laptop lid is open, the built-in screen can be used as a second monitor in mirrored or extended mode. Two external monitors connected to the docking station may work. It depends on the specific laptop and docking station. If two external monitors can be used, the laptop screen will be black, even if the lid is open. But many Haswell Docking Stations only work with a single external monitor. Page 8
Haswell Docking Stations DisplayPort Multi-Stream Transport (MST) Allows multiple independent video streams on a single port. Used to daisy-chain multiple monitors on a single connection. This technology is not supported in the version of Linux used with XenClient. For details see: http://www.displayport.org/cables/driving-multiple-displays-from-a-single-displayport-output MST and Haswell Laptops Many Haswell laptops use MST to integrate with the docking station. This appears to be an emerging design trend among the main laptop vendors. The docking station, or in some cases the laptop itself, is effectively acting as a DisplayPort hub. Implications for XenClient XenClient cannot support multiple monitors connected to a docking station if MST is used. Typical behavior: Both monitors light up but the Engine will act as if only a single monitor is attached. The monitors will be stuck in mirrored mode with no option for extended mode. One or both monitors may experience display issues such as flickering, distortion, or letterboxing. Page 9
Dual-Monitor Testing Notes for Selected Docking Stations Laptop Lenovo X230, T430, T530 Docking Station Platform Type Results With Two External Monitors MiniDock 3 IvyBridge Works in either mirrored or extended mode. Lenovo X240, T440, T540 UltraDock Haswell The Engine behaves as if only a single monitor is attached. Video output is mirrored between the two external monitors with no option for extended mode. Dell E6330, E7230 Dell E6440 E-Port Plus IvyBridge Works in either mirrored or extended mode. E-Port Plus Haswell The same docking station is used for Dell Haswell and IvyBridge laptops. For this particular Dell Haswell laptop, the docking station works with dual external monitors in either mirrored or extended mode. Same docking station as used with the Haswell E6440, but with different results. Dell E7240, E7440 E-Port Plus Haswell The Engine behaves as if only a single monitor is attached. Video output is mirrored between the two external monitors with no option for extended mode. Speculative conclusion: These laptops use DisplayPort MST to integrate with the docking station video ports, but the MST technology is internal to the laptops, not in the docking station. HP 850-G1, 1040-G1 UltraSlim Dock Haswell Inconsistent and unstable results. Sometimes the external monitors get stuck in mirrored mode. Other times it is possible to configure the monitors into external mode but after a while the monitors will spontaneously return to mirrored mode. Page 10
3D Graphics in XenClient VMs with Intel GVT
3D Graphics in XenClient VMs 3D Graphics and Intel GVT XenClient 5.5 now supports 3D acceleration in VMs deployed to Intel Haswell platforms. This is done by leveraging Intel GVT (Graphics Virtualization Technology, formerly known as XenGT). No special drivers or configuration is required to enable GVT in XenClient VMs. Any Win7 or Win8 VM deployed to a GVT-capable platform should automatically get GVT graphics. Although GVT can be disabled in Synchronizer policies if desired. 3D Performance in XenClient VMs For a single VM running on a Haswell endpoint, 3D graphics performance should be close to native. Performance scales down with multiple VMs because the GPU is being shared. 3D performance should be more than adequate for most business applications. Including Google Earth and the Windows Aero interface. By far the two most requested 3D applications in pre-5.5 XenClient versions. Page 12
Simplified Intel VGT Architecture VM Layer The native Intel graphics driver is installed in each VM. As far as the driver is concerned, it has direct access to a physical GPU. Dom0 VM1 VM2 Hypervisor Layer Xen hypervisor manages GPU partitioning and mediates pass-through of virtual GPUs. Xen GVT Layer Intel GVT technology partitions the physical GPU into multiple virtual GPUs. Virtual GPU Virtual GPU Virtual GPU Processor Layer Intel Haswell processor includes multiple CPU cores and an integrated GPU. Page 13
Graphics Aperture BIOS Settings Graphics Aperture is a memory resource required for GVT VMs. These screen shots provide an example of how the graphics aperture may be adjusted in the BIOS. Default value was 256 MB, which is only sufficient for a single GVT-enabled VM (plus dom0). Maximum value is 512 MB, which should support up to three GVT-enabled VMs (plus dom0). This example is for a Lenovo x240. The original factory BIOS did not permit graphics aperture adjustment. Increasing the graphics aperture was only possible after a BIOS upgrade. Page 14
Intel GVT Resources The following resources are provided on a for information only basis for XenClient users who may be interested in learning more about GVT technology. Certain sections of these resources may not be applicable to the specific implementation of GVT interoperability in XenClient enterprise. Note that XenGT is an older and now deprecated name for the family of Intel processor features now known as GVT. Resource Description Provides a high-level overview of GVT features in Intel Haswell processors. https://01.org/blogs/skjain/2014/intel%c2%ae-graphicsvirtualization-update http://events.linuxfoundation.org/sites/events/files/slides/xengt- LinuxCollaborationSummit-final_1.pdf Good overview of GVT architecture and how it compares to other options for graphics virtualization. https://01.org/xen/blogs/srclarkx/2013/graphics-virtualization-xengt Written from a Xen perspective. Describes how the hypervisor integrates with Intel GVT. Page 15
Graphics Drivers in XenClient VMs and Synchronizer Graphics Policy Settings
Graphics Drivers for XenClient VMs This table outlines the options for graphics drivers in XenClient VMs. Windows Versions Platform Requirements Support Status 3D Graphics Rendering 3D Graphics Performance Intel HD Graphics Driver Win7 or Win8 Intel Haswell CPU with integrated Intel graphics. Supported. Default for Win7 or Win8 VMs deployed to Haswell endpoints. Hardware 3D acceleration. Close to native performance for a single VM. Win8 WDDM Driver Win8 Only No specific requirements. Supported. Default for Win8 VMs deployed to non-haswell endpoints. Software 3D rendering using the Windows 8 built-in kernel-mode rendering library. Generally adequate for lightweight 3D apps (like Google Earth). 3D rendering will cause high CPU utilization. Win7 WDDM Driver Win7 Only No specific requirements. Unsupported and Highly Experimental. Only available through Synchronizer policy configuration. Software 3D rendering using an external usermode rendering library. Similar to Win8 WDDM, but some applications may experience performance or stability issues. Win7 XPDM Driver Win7 Only No specific requirements. Supported. Default for Win7 VMs deployed to non-haswell endpoints. None. Applications may implement their own 3D rendering but performance will generally be poor. Page 17
Graphics Drivers in Windows Device Manager The graphics architecture in place for a particular VM can be inferred from the display adapter entry in Windows device manager. Native Intel HD Graphics Driver Requires Intel Haswell CPU with integrated Intel Graphics. Default for Win7 or Win8 VMs deployed to Haswell endpoints. VM has direct access to GPU for hardware 3D acceleration. Windows 8 WDDM Driver Default for Win8 VMs deployed to pre-haswell endpoints. Software 3D rendering with the built-in Windows 8 library. Windows 7 WDDM Driver Optional for Win7 VMs deployed to pre-haswell endpoints. Software 3D rendering with an external library. This driver is unsupported and highly experimental! Windows 7 XPDM Driver Default for Win7 VMs deployed to pre-haswell endpoints. No 3D rendering capabilities. Page 18
Synchronizer Policy Settings for Graphics Page 19
Synchronizer Policy Details Enable Graphics Virtualization Enables GVT graphics for Windows 7 or Windows 8 VMs deployed to GVT-capable endpoints. Enabled by default, but can be disabled on a per-vm basis. Enable 3D Graphics Only applies to Windows 7 VMs. Enables 3D software rendering with a WDDM driver on non-gvt endpoints. Disabled by default. May be enabled on a per-vm basis. This feature is currently considered to be unsupported and highly experimental. It may cause performance or stability issues with some Windows applications. Page 20
Which Graphics Driver Will Be Installed in the VM? Yes Is the VM deployed to a Yes GVT-capable endpoint? No Is the Enable Graphics Virtualization policy setting enabled? No Yes Win8 What is the VM OS Type? Win7 Yes Is the Enable 3D Graphics policy setting enabled? No Native Virtualized graphics with hardware 3D acceleration. Win8 PV (WDDM) Emulated graphics with the standard Windows 8 3D rendering library. Win7 PV (WDDM) Emulated graphics with an external 3D rendering library. Unsupported and experimental. Win7 PV (XPDM) Emulated graphics with no 3D rendering. Page 21