Xen Project Release Features

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Icon Info.png Note that for Xen 4.10or newer this information is in the SUPPORT.md file in the source tree and tarball. A generated web-page for 4.10 or newer can be found here.


Legend:

  • : Feature
  • : Partial
  • : Removed
  • For definitions of experimental, preview, supported and deprecated see here

Xen 4.10 or Newer

The matrix is generated with the relevant tree, aka

Archive

To make the table more usable, we have archived information related to older releases in

Overview

Xen 4.4 Xen 4.5 Xen 4.6 Xen 4.7 Xen 4.8 Xen 4.9
Initial Release 10 March 2014 15 Jan 2015 13 Oct 2015 20 June 2016 5 Dec 2016 28 June 2017
Supported until Sept 2015 July 2016 April 2017 Dec 2017 June 2018 Jan 2019
Security support until March 2017 Jan 2018 Oct 2018 June 2019 Dec 2019 July 2020
Feature List FL 4.4 FL 4.5 FL 4.6 FL 4.7 FL 4.8 FL 4.9
Release Notes RN 4.4 RN 4.5 RN 4.6 RN 4.7 RN 4.8 RN 4.9
Supported Mainline Architectures for the hypervisor (Host)
X86-64
ARM v7 + Virtualization Extensions [ 8 ] [ 14 ] [ 26 ] [ 26 ] [ 26 ]
ARM v8 [ 8 ] [ 15 ] [ 15 ] [ 15 ] [ 15 ]
Guest Types
For X86 Architectures
Paravirtualised
Traditional Xen Project PV guest
HVM Guest [ 1 ]
Fully virtualised guest using hardware virtualisation extensions
PV-on-HVM Guest [ 1 ]
Fully virtualised guest using PV extensions/drivers for improved performance
PVH Guest preview preview
added PVH Dom0
preview preview preview
started implementing PVHv2
preview
removed PVHv1
For ARM Architectures
ARM Guest
Optimal combination of full virtualization and PV extensions


Limits

Xen 4.4 Xen 4.5 Xen 4.6 Xen 4.7 Xen 4.8 Xen 4.9 - 4.11
Host Limits
For X86 Architectures
Physical CPUs 4095 4095 4095 4095 4095 4095
Physical RAM 16TB 16TB 16TB 16TB 16TB 16TB
For ARM Architectures
Physical CPUs 8 8 8 for 32bit; 128 for 64bit 8 for 32bit; 128 for 64bit 8 for 32bit; 128 for 64bit 8 for 32bit; 128 for 64bit
Physical RAM 16GB 16GB for 32bit, 5TB for 64bit 16GB for 32bit, 5TB for 64bit 16GB for 32bit, 5TB for 64bit 16GB for 32bit, 5TB for 64bit 16GB for 32bit, 5TB for 64bit
Guest Limits
X86 PV Guest Limits
Virtual CPUs 512 512 512 512 512 512
Virtual RAM 512GB 512GB 512GB > 1TB > 1TB > 1TB
X86 HVM Guest Limits
Virtual CPUs 128 128 128 128 128 128
Virtual RAM 1TB 1TB 1TB 1TB 1TB 1TB
ARM Guest Limits
Virtual CPUs 8 8 8 for 32bit; 128 for 64bit 8 for 32bit; 128 for 64bit 8 for 32bit; 128 for 64bit 8 for 32bit; 128 for 64bit
Virtual RAM 16GB 1TB [ 7 ] 1TB [ 7 ] 1TB [ 7 ] 1TB [ 7 ] 1TB [ 7 ]
Number of event channels
Event Channels 131072 131072 131072 131072 131072 131072



Toolstack and Tools

Xen 4.4 Xen 4.5 Xen 4.6 Xen 4.7 Xen 4.8 Xen 4.9
Toolstack
Built-in
xend / xm deprecated removed
XL
Qemu based disk backend (qdisk) for XL
[ 5 ] [ 5 ] [ 5 ] [ 5 ] [ 5 ] [ 5 ]
XL Open vSwitch integration
systemd support
JSON support infrastructure only, no tools support infrastructure only, no tools support infrastructure only, no tools support infrastructure only, no tools support infrastructure only, no tools support
AHCI support
PVUSB
HVM USB passthrough
QEMU backend hotplugging
Soft-Reset
3rd Party
libvirt driver for XL [ 29 ] [ 29 ] [ 16 ] [ 29 ] [ 16 ] [ 29 ] [ 16 ] [ 29 ] [ 16 ] [ 29 ]
Tooling
gdbsx
debugger to debug ELF guests
[ 12 ] [ 12 ] [ 12 ] [ 12 ] [ 12 ]
vPMU
Virtual Performance Management Unit for HVM guests
[ 4 ] [ 4 ][ 12 ] [ 4 ][ 12 ] [ 4 ][ 12 ] [ 4 ][ 12 ] [ 4 ][ 12 ]
Serial console Add Oxford PCIe, and Broadcom TrueManage support
xentrace
performance analysis
[ 12 ] Added Xenalyze


Features

Xen 4.4 Xen 4.5 Xen 4.6 Xen 4.7 Xen 4.8 Xen 4.9
Advanced Memory Management
Memory Ballooning
Memory Sharing
allow sharing of identical pages between HVM guests
preview [ 3 ] preview [ 3 ][ 12 ] preview [ 3 ][ 12 ] preview [ 3 ][ 12 ] preview [ 3 ][ 12 ] preview [ 3 ][ 12 ]
Memory Paging
allow pages belonging to HVM guests to be paged to disk
preview [ 3 ] preview [ 3 ][ 12 ] preview [ 3 ][ 12 ] preview [ 3 ][ 12 ] preview [ 3 ][ 12 ] preview [ 3 ][ 12 ]
TMEM - Transcendent Memory experimental [ 2 ] experimental [ 2 ][ 12 ] experimental [ 2 ][ 12 ] experimental [ 2 ][ 12 ] experimental [ 2 ][ 12 ] experimental [ 2 ][ 12 ]
Resource Management
Cpupool
advanced partitioning
Credit 2 Scheduler
designed for latency-sensitive workloads and very large systems.
experimental experimental experimental (significant additions)
RTDS Based Scheduler
Real-time CPU scheduler built to provide guaranteed CPU capacity to guest VMs on SMP hosts.
experimental experimental experimental (significant additions) experimental experimental
Null Scheduler
Scheduler for embedded workloads where 0-scheduling overhead is required
preview [ 28 ]
NUMA scheduler affinity [ 12 ] [ 12 ] [ 12 ] [ 12 ] [ 12 ]
Scalability
1GB/2MB super page support
Deliver events to PVHVM guests using Xen event channels
Fair locks (ticket-locks)
High Availability and Fault Tolerance
Live Migration, Save & Restore [ 12 ] [ 18 ] Migration v2 [ 23 ] [ 23 ] [ 23 ]
Remus Fault Tolerance improvements
for COLO
[ 10 ][ 12 ]
Remus ported to Migration v2
COLO Manager experimental [ 24 ] experimental [ 24 ] experimental [ 24 ]
X86 vMCE
Forward Machine Check Exceptions to Appropriate guests
Network and Storage
Online resize of virtual disks
Security (also see this presentation or this document)
Driver Domains
Device Model Stub Domains [ 12 ] [ 12 ][ 17 ] [ 12 ][ 17 ] [ 12 ][ 17 ] [ 12 ][ 17 ]
Kconfig experimental experimental experimental
Live Patching preview [ 22 ] preview (added ARM support) [ 27 ], ARM support still in preview
Virtual Machine Introspection (Memaccess and VM Event APIs)
enabling integration of 3rd party security solutions into Xen virtualized environments
improvements[ 12 ] [ 19 ] reworked with ARM support, added VM Event APIs improvements
XSM & FLASK
mandatory access control policy providing fine-grained controls over Xen domains, similar to SELinux
[ 17 ] [ 17 ] [ 17 ] [ 17 ]
XSM & FLASK support for IS_PRIV [ 17 ] [ 17 ] [ 17 ] [ 17 ]
vTPM Support
vTPM 2.0


Interoperability / Hardware Support

Xen 4.4 Xen 4.5 Xen 4.6 Xen 4.7 Xen 4.8 Xen 4.9
X86
X86 Nested Virtualisation
Running a hypervisor inside an HVM guest
preview preview [ 11 ] preview [ 11 ] preview [ 11 ] preview [ 11 ] preview, fixes [ 11 ]
HVM PXE Stack (x86) gPXE iPXE iPXE iPXE iPXE iPXE
Physical CPU Hotplug [ 12 ] [ 12 ] [ 12 ] [ 12 ] [ 12 ]
Physical Memory Hotplug [ 12 ] [ 12 ] [ 12 ] [ 12 ] [ 12 ]
Support for PV kernels in bzImage format [ 12 ] [ 12 ] [ 12 ] [ 12 ] [ 12 ]
PCI Passthrough [ 12 ] [ 12 ][ 13 ] [ 12 ] [ 12 ] [ 12 ] [ 12 ]
X86 Advanced Vector eXtension (AVX) AVX-512
Intel Platform QoS Technologies preview: CMT preview: CAT, MBM preview: CDP preview: CDP preview: CDP
Other Intel® Xeon® Features [ 25 ] [ 25 ] [ 25 ]
ARM
64K Guest Pages
ACPI / SBBR Compliance experimental; ACPI 6.0+ experimental experimental
ACPI guest support with UEFI with UEFI
PCSI Compatibility v0.1 & 0.2 v1.0 v1.0 v1.0
ARM® Interrupt Virtualization GiC v2 GiC v2m/GiC v3 improvements to v2/v3
Wallclock support


Device Models and Virtual Firmware

Xen 4.4 Xen 4.5 Xen 4.6 Xen 4.7 Xen 4.8 Xen 4.9
Device Models and Virtual Firmware for HVM guests
For X86 Architectures
Traditional Device Model
Device emulator based on Xen fork of Qemu
Qemu Upstream Device Model
Device emulator based on upstream Qemu
default, unless stubdomains are used default, unless stubdomains are used default, unless stubdomains are used default, unless stubdomains are used default, unless stubdomains are used default, unless stubdomains are used
DMOP (Device Model Operation Hypercall) [ 28 ]
ROMBIOS
BIOS used with traditional device model only
SeaBIOS
BIOS used with upstream qemu device model and XL only
OVMF/Tianocore
UEFI Firmware used with upstream qemu device model and XL only
experimental [ 4 ] experimental [ 4 ] experimental [ 4 ] + ARM support experimental [ 4 ] + ARM support experimental [ 4 ] + ARM support experimental [ 4 ] + ARM support
PV Bootloader support
For X86 Architectures
PyGrub support for GRUB 2
PyGrub support for /boot on ext4
pvnetboot support
Bootloader supporting network boot of PV guests


PV Protocols and Drivers

Xen 4.4 Xen 4.5 Xen 4.6 Xen 4.7 Xen 4.8 Xen 4.9
Common
net, block, console, keyboard=kbd, mouse framebuffer=fb
[ 28 ]
USB [ 28 ]
pvcalls
POSIX function call forwarding
preview [ 28 ]
9pfs
share a filesystem between VMs (a requirement for adding Xen support to many container engines)
preview [ 28 ]
sndif (sound device)
used in automotive/embedded
preview [ 28 ]
displif (display)
used in automotive/embedded
preview [ 28 ]


Notes

[ 0 ] Compile time limit, can be increased
[ 1 ] Requires hardware virtualisation support
[ 2 ] Disabled by default (enable with hypervisor command line option). Not supported in production and doesn't have full security support
[ 3 ] Preview, due to limited tools support. Hypervisor side in good shape
[ 4 ] Disabled by default (enable with hypervisor command line option)
[ 5 ] Used as a fallback if blkback and/or blktap2 are not available
[ 6 ] See Xen ARM with Virtualization Extensions; basic functionality implemented; lack of real hardware to validate against
[ 7 ] Limited by supported host memory
[ 8 ] Tested on Broadcom 7445D0 A15, Midway (Calxeda), Odroid-XU, OMAP5, OMAP6, DRA7 (Texas Instrument), Exynos5 (Samsung), SunXI (AllWinner) aka A20/A21, CubieTruck, CubieBoard
[ 9 ] Tested on Vexpress (ARM Ltd.), Seattle (AMD), Mustang (Applied Micro-X-Gene), McDivitt aka HP Moonshot cartridge (Applied Micro X-Gene)
[ 10 ] Remus has been ported to XL and has been tested with COLO which is currently outside the Xen tree, but planned to be included in Xen 4.6. Also see Remus Toolkit Differences explaining differences between Remus with XM (not supported in Xen 4.5) and XL
[ 11 ] There are a number of reported crashes that have not yet been fixed and some known limitations
[ 12 ] Not yet supported on ARM; for a more detailed update on what is supported on ARM see here and here
[ 13 ] The PCI passthrough features did not make it on time for Xen 4.5, but doing passthrough of MMIO regions did. In the ARM world it is quite common to have no PCIe devices and to only access devices using MMIO regions. As such this feature allows us to have driver domains be in charge of network or storage devices.
[ 14 ] Added the following platforms to [ 8 ]: Renesas R-Car Gen2, Huawei hip04-d04
[ 15 ] Added the following platforms to [ 9 ]: Thunder X (partial), Xilinx ZynqMP SoC
[ 16 ] Now tested as part of Xen Project Test Lab and OpenStack CI Loop
[ 17 ] Now tested as part of Xen Project Test Lab
[ 18 ] Migration v2: see [1] and [2]. VM migration using libvirt between two hosts is now tested. Live Migration between hosts of different Xen versions is now tested.
[ 19 ] The memory event subsystem has been reworked and extended to a new VM event subsystem. The new VM event subsystems supports both the ARM and x86 architectures.
[ 20 ] Passthrough for non-PCI devices allows users to passthrough devices via partial device trees.
[ 21 ] Dates for historical releases have not be researched.
[ 22 ] The code for hypervisor live patching is NOT enabled by default. When compiling the hypervisor one must change the config to build it. Note that Live Patching is currently only supported on x86. For more information on live patching, see LivePatch.
[ 23 ] CPU ID Levelling enables migration of VM’s between a larger range of non-identical hosts than previously supported.
[ 24 ] The COLO Manager has been fully integrated as an experimental feature into Xen 4.7. Note that the COLO Block Replication and COLO Proxy components, both of which are QEMU components, are currently still reviewed by the QEMU community. Both components are available as out-of-tree add-ons to the Xen Project Hypervisor, until fully integrated into QEMU.
[ 25 ] Added experimental support for VT-d Posted Interrupts, VMX TSC Scaling, Memory Protection Keys
[ 26 ] Removed support for Huawei hip04-d04
[ 27 ] See xen-devel discussion "livepatch: Declare live patching as a supported feature"
[ 28 ] See xen-devel discussion "Updating https://wiki.xenproject.org/wiki/Xen_Project_Release_Features to reflect support status of new features"
[ 29 ] Security support via libvirt.org/securityprocess