Xen Project: Windows PV Drivers
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The document provides an overview of the Xen Project Windows PV drivers, detailing their background, legacy issues, and the transition to standard drivers. It discusses driver types, compatibility, installation, and building processes, highlighting advancements in driver functionality and the push for open-source development. Key project leadership and community involvement are also emphasized, along with deployment challenges and driver-specific advantages and disadvantages.
![Building
• BUILD.md should tell you want you need to know
• Pre-requistes
• Visual Studio 2012 (NOT Express) or 2013 (Express OK)
• Windows 8 or 8.1 WDK
(See http://msdn.microsoft.com/en-us/windows/hardware/hh852365)
• Python 3.x
• Set environment
• KIT
• SYMBOL_SERVER
• build.py free|checked [nosdv]
• Latest development builds available for download:
(See http://www.xenproject.org/downloads/windows-pv-drivers/development-builds.html)
Usually C:Program FilesWindows Kits8.0
I use C:Symbols](https://image.slidesharecdn.com/xenprojectwindowspvdrivers-150206065546-conversion-gate02/85/Xen-Project-Windows-PV-Drivers-20-320.jpg)
Xen Project: Windows PV Drivers
- 1. Xen Project Windows PV Drivers Paul Durrant Project Lead
- 2. Agenda • Background • Origin of the drivers • Legacy, Standard and XenProject drivers • Driver interfaces • Discovery • Compatibility • Building and Installing drivers • Tools
- 3. Terminology PDO FDO FDO PACKAGE (INF FILE) PACKAGE local/domain/device/vif This is a Function Device Object, created when a driver binds to a Physical Device Object. The INF file states the ‘names’ it will bind to. This is a Physical Device Object, created by a bus driver. The ‘name’ of this device is used by Windows to select a driver. This is a xenstore key that is used by a PV bus driver to create a PDO. This is an FDO created by a child PV driver that binds to the PDO representing the xenstore key. FiltDO This is a Filter Device Object. They can be used to interpose on Plug’n’Play, Power or IO messages flowing between PDOs and FDOs.
- 4. Legacy Drivers • Used for all versions of Windows in Citrix XenServer 6.0 • Used only for Windows XP and Server 2003 from XenServer 6.1 • Closed source • Code of unknown origin made open source difficult
- 5. Legacy Drivers ROOTXENEVTCHN PCIVEN_5853&DEV_0001 XENVBDXENEVTCHN DISK XENVIF XENNET XENUTIL XENVBDXEVTCHN XENVIF XENNET local/domain/device/vif local/domain/device/vif/0 XENNET XENNET local/domain/device/vif/1 local/domain/device/vbd/768 DISK local/domain/device/vbd/832 SCSIFILT SCSIFILT …… Created by installer Emulated by QEMU Standard in-box driver Linkage dependency • XENIFACE omitted for simplicity
- 6. Legacy Drivers Problems: • SCSIFILT makes storage stack complicated • Cross-package linkage dependencies make upgrade very tricky • Binary incompatibility can lead to hard-to-diagnose BSODs • Two root nodes make load order unpredictable and initialization of PV interfaces very fragile • Use of synthetic root node requires an installer • Windows Update cannot be used to deploy “But Windows Update would be very useful for large installations or upgrades so that’s a pain. What can we do?”
- 7. Standard Drivers • Used for versions of Windows from Vista onwards from XenServer 6.1 • Built using Windows 8 WDK and Visual Studio 2012 • Necessary for supporting Windows 8 onwards • Anticipated to become open source • All code of unknown origin was removed
- 8. PCIVEN_5853&DEV_0002 XENVBD DISK XENVIF XENNET XENVBDXENVIF XENNET local/domain/device/vif local/domain/device/vif/0 XENNET XENNET local/domain/device/vif/1 local/domain/device/vbd/768 DISK local/domain/device/vbd/832 …… local/domain/device/vbd XENBUS XENBUS XENFILT XEN NOTE: New Device ID Handles unplug Standard Drivers • XENIFACE omitted again for simplicity
- 9. Standard Drivers Advantages: • STORPORT instead of SCSIPORT • No need for SCSIFILT • Independent packages • No binary compatibility issues • No installation ordering issues • Just PCI root node • Windows Update now possible
- 10. Standard Drivers Problems: • New Device ID • Conceived to allow Windows Update deployment, but… • Caused big problems in XenServer 6.1 • Not acceptable to upstream community (e.g. Amazon) • Compatibility checks don’t behave well • Still an assumption that drivers will be installed or upgraded together
- 11. Xen Project Drivers • XenServer went fully open source in 2013 • Desire for Windows PV drivers to become even more open • Drivers already functioning on most Xen installations • Amazon already building from source • Windows PV Drivers sub-project ratified in June 2014 • Front page accessible from http://www.xenproject.org • Source repositories at http://xenbits.xenproject.org • Project lead: Paul Durrant • Committers: Paul Durrant, Ben Chalmers and Owen Smith
- 12. Xen Project Drivers • Plan to use for all versions of Windows from XenServer vNext • Windows 2003 goes out of support in May 2015 • Built using Windows 8 WDK and Visual Studio 2012 • Cannot move to 8.1 WDK as Windows 7 is not supported • Source is buildable with 8.1 WDK and Visual Studio 2013 • Remaining problems from Standard Drivers addressed
- 13. PCIVEN_5853&DEV_XXXX XENVBD DISK XENVIF XENNET XENVBDXENVIF XENNET local/domain/device/vif local/domain/device/vif/0 XENNET XENNET local/domain/device/vif/1 local/domain/device/vbd/768 DISK local/domain/device/vbd/832 …… local/domain/device/vbd Interface discovery: • More on this… NOTE: Flexible Device ID: • More on this… Xen Project Drivers • XENIFACE still omitted for simplicity XENBUS XENBUS XENFILT XEN
- 14. Flexible Device ID PCIVEN_5853&DEV_0001 PCIVEN_5853&DEV_0002 PCIVEN_5853&DEV_C000 You should have one of these You may have one of these • XENBUS binds to any of these • Co-installer selects ‘active’ device • Will only select if there’s no current selection • Only active device has children • Child PDO name carries device ID • XenServer has reserved C000 for Windows Update
- 15. Interface Discovery • IRP_MN_QUERY_INTERFACE message • Identifies interface by GUID • Gets back jump table and context DRIVER3 DRIVER3 DRIVER3 • Message may be forwarded to parent if interface not implemented • Client doesn’t care where the interface is implemented • Allows interfaces to be exported by XENFILT • Unplug
- 16. Interface Discovery Example XENBUS XENVIF • XENVIF codebase imports evtchn_interface.h from XENBUS • XENVIF allocates a XENBUS_EVTCHN_INTERFACE structure and passes it to XENBUS in IRP_MN_QUERY_INTERFACE message • Always requests XENBUS_EVTCHN_INTERFACE_VERSION_MAX IRP_MN_QUERY_INTERFACE
- 17. Interface Discovery Example XENBUS XENVIF • XENBUS fills in structure with requested interface version • XENBUS completes IRP • XENVIF calls XENBUS_EVTCHN(Acquire, …) • Acquisition not implicit in query • References must be dropped across S4 transition (Hibernate) • IRP_MN_QUERY_INTERFACE must be issued at PASSIVE_LEVEL XENBUS_EVTCHN_INTERFACE
- 18. Interface Discovery Example Compatibility: • XENVIF binds to a particular PDO revision • Each PDO revision maps to a set of interface versions • XENVIF subscribes to interface • Co-installer writes version to HLKM/CurrentControlSet/Services/XENBUS/Interfaces/XENVIF/EVTCHN • XENBUS maintains compatibility • Change of interface version implies updated binding revision • Subscribers don’t need to be concerned with older versions of providers • Co-installer checks subscribers and vetoes upgrade if interface versions are not implemented • Ensures subscribers are updated before providers
- 19. Available Interfaces • XENFILT • UNPLUG • EMULATED • XENBUS • DEBUG • SUSPEND • SHARED_INFO • EVTCHN • STORE • RANGE_SET • CACHE • GNTTAB • XENVIF • VIF
- 20. Building • BUILD.md should tell you want you need to know • Pre-requistes • Visual Studio 2012 (NOT Express) or 2013 (Express OK) • Windows 8 or 8.1 WDK (See http://msdn.microsoft.com/en-us/windows/hardware/hh852365) • Python 3.x • Set environment • KIT • SYMBOL_SERVER • build.py free|checked [nosdv] • Latest development builds available for download: (See http://www.xenproject.org/downloads/windows-pv-drivers/development-builds.html) Usually C:Program FilesWindows Kits8.0 I use C:Symbols
- 21. Installing • INSTALL.md should tell you want you need to know • Driver build results in directory and tarball • Copy to target (and unpack if necessary) • Navigate to x86 or x64 • Either run dpinst.exe or use Device Manager • Builds are test signed • Install .pfx file to avoid scary warning • Make sure testsigning is enabled on 64-bit systems bcdedit /set testsigning on
- 22. Contributing • See MAINTAINERS file • Follow guidance at http://wiki.xen.org/wiki/Submitting_Xen_Patches • Subscribe to mailing list win-pv-devel@lists.xenproject.org (See http://lists.xenproject.org/cgi-bin/mailman/listinfo/win-pv-devel)
- 23. Q & A