Xen 4.3 Feature List

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Fill these out based on Xen_Roadmap/4.3 and Xen_4.3_Release_Notes. Also ensure that links containing 4.3-testing and supported-xen-43-series exist.


High Level Features

See this table for a comparison of the feature sets of different Xen releases. Compatibility information can be found in the following two tables: Host Operating Systems and Guest Operating Systems.

Note that Linux Distributions and other operating systems, will upgrade to Xen 4.3 according to their own release schedules.

ARM Support

Xen 4.3 includes support for ARMv7-A Virtualization Extensions and the ARMv8 architecture. This support is classified as Technology Preview and is aimed at supporting ARM based servers when these are available. ARMv7 support has been validated on the Arndale Board, the Samsung XE303C12-A01 Chromebook, ARM Fast Models and the ARM Versatile Express. ARMv8 support has only been validated on ARM Fast Models. However, the Xen community is working with several ARM server hardware vendors to ensure that Xen will work with ARM servers, when these are available. More Info ...

Performance and Scalability Enhancements

NUMA scheduler affinity has led to significant performance improvements on NUMA hardware. Scalability improvements increased support for physical RAM on hosts from 5TB to 16TB of RAM. A tool stack bottleneck limitation to 300 virtual CPUs was removed and Xen 4.3 has been tested for up to 750 virtual CPUs. With block protocol scalability improvements, users will see significant improvement in read/write performance and throughput with more than 6 guests on a single host. More on NUMA ... More on Block Protocol Scalability ...

Improved Security

Besides including the latest security fixes (up to XSA 55), Xen 4.3 contains major improvements to it advanced security features.

  • vTPM Enhancements: Xen 4.3’s virtual Trusted Platform Module (vTPM) subsystem has been extended to enable guest operating systems to more easily interact with it. Each guest now has access to unique emulated software but can only access keys that are released by a special vTPM manager domain. More Info ...
  • The scope of the XSM/Flask security subsystem has been extended to cover both privileged and unprivileged APIs. This allows organizations like the NSA to further enhance Xen Project’s security by breaking down the control domain into smaller, compartmentalized units. More Info ...

More information on Xen and security at Xen and Security.

Upstream QEMU

QEMU Upstream is now the default for Virtual Machines that do not use stub domains. You can revert to QEMU traditional by adding 

device_model_version = "qemu-xen-traditional"

to your config file. QEMU upstream now supports:

  • PCI Passthrough
  • XL cd-{insert,eject}
  • And enables dirtybit tracking during VM migration

Restrictions:

  • QEMU upstream does not yet work with stub domains. Stub domains will still be created with qemu-traditional.

Toolstack Improvements

A number of additional features have been added to XL in Xen 4.3

  • XL now accept several USB devices, rather than only one. You can use the following syntax:
usbdevice=["device1","device2",...]
The old format is still supported.

Usability improvements

Xen 4.3 now installs into /usr/local by default.

Power Efficiency

Xen 4.3's cpuidle infrastructure now uses the MWAIT extension for all the processors that support it (modern Intel chips, i.e., Sandy Bridge, Ivy Bridge and later). This improves Xen Project’s power efficiency on those processors.

Tools

In Xen 4.3 the Serial Console was extended to support EHCI debug ports.

Documentation

You can find Xen 4.3 documentation in the following two locations:

Acknowledgements

We wanted to thank the various contributors to Xen 4.3 : for a complete list of contributions check the Xen 4.3 Acknowledgements.

Downloads

Xen 4.3 (and update releases) can be downloaded from the 4.3 Download Archives.

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