Xen Project Release Features
Legend: ✓: Feature ✓: Partial
| Xen 4.0 | Xen 4.1 | Xen 4.2 | Xen 4.3 | Xen 4.4 | Xen 4.5 | |
|---|---|---|---|---|---|---|
| Initial Release | 7 April 2010 | 25 March 2011 | 17 Sept 2012 | 9 July 2013 | 10 March 2014 | 15 Jan 2015 |
| Feature List | FL 4.2 | FL 4.3 | FL 4.4 | FL 4.5 | ||
| Release Notes | RN 4.0 | RN 4.1 | RN 4.2 | RN 4.3 | RN 4.4 | RN 4.5 |
| Supported Mainline Architectures for the hypervisor (Host) | ||||||
| IA-A32 | ✓ | ✓ | ✓ | ✗removed | ||
| X86-64 | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| Itanium (ia64) | ✓ | ✓deprecated in this release | ✓deprecated | ✗removed | ||
| ARM v7 + Virtualization Extensions | ✓preview [ 6 ] | ✓ | ✓ [ 8 ] | |||
| ARM v8 | ✓preview [ 6 ] | ✓ | ✓ [ 9 ] | |||
| 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 | ||||
| For ARM Architectures | ||||||
| ARM Guest Optimal combination of full virtualization and PV extensions |
✓preview [ 6 ] | ✓ | ✓ | |||
| Host Limits | ||||||
| For X86 Architectures | ||||||
| Physical CPUs | 128 [ 0 ] | >255 | 4095 | 4095 | 4095 | 4095 |
| Physical RAM | 1TB | 5TB | 5TB | 16TB | 16TB | 16TB |
| For ARM Architectures | ||||||
| Physical CPUs | 8 | 8 | 8 | |||
| Physical RAM | 16GB | 16GB | 16GB for 32bit, 5TB for 64bit | |||
| Guest Limits | ||||||
| X86 PV Guest Limits | ||||||
| Virtual CPUs | 128 | >255 | 512 | 512 | 512 | 512 |
| Virtual RAM | 512GB | 512GB | 512GB | 512GB | 512GB | 512GB |
| X86 HVM Guest Limits | ||||||
| Virtual CPUs | 128 | 128 | 256 | 256 | 256 | 256 |
| Virtual RAM | 1TB | 1TB | 1TB | 1TB | 1TB | 1TB |
| ARM Guest Limits | ||||||
| Virtual CPUs | 8 | 8 | 8 | |||
| Virtual RAM | 16GB | 16GB | 1TB [ 7 ] | |||
| Number of event channels | ||||||
| Event Channels | 1024/4096 | 1024/4096 | 1024/4096 | 1024/4096 | 131072 | 131072 |
| Toolstack | ||||||
| Built-in | ||||||
| xend / xm | ✓ | ✓ | ✓deprecated in this release | ✓deprecated | ✓deprecated | ✗removed |
| XL | ✓initial implementation | ✓preview release | ✓ | ✓ | ✓ | ✓ |
| Qemu based disk backend (qdisk) for XL |
✓ [ 5 ] | ✓ [ 5 ] | ✓ [ 5 ] | ✓ [ 5 ] | ✓ [ 5 ] | |
| XL Open vSwitch integration | ✓preview | ✓ | ✓ | |||
| systemd support | ✓ | |||||
| JSON support | ✓infrastructure only, no tools support | |||||
| 3rd Party | ||||||
| libvirt driver for XL | ✓ | ✓ | ✓ | ✓ | ✓ | |
| Features | ||||||
| Advanced Memory Management | ||||||
| Memory Ballooning | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| Memory Sharing allow sharing of identical pages between HVM guests |
✓preview | ✓preview | ✓preview [ 3 ] | ✓preview [ 3 ] | ✓preview [ 3 ] | ✓preview [ 3 ][ 12 ] |
| Memory Paging allow pages belonging to HVM guests to be paged to disk |
✓preview | ✓preview | ✓preview [ 3 ] | ✓preview [ 3 ] | ✓preview [ 3 ] | ✓preview [ 3 ][ 12 ] |
| TMEM - Transcendent Memory | ✓experimental [ 2 ] | ✓experimental [ 2 ] | ✓experimental [ 2 ] | ✓experimental [ 2 ] | ✓experimental [ 2 ] | ✓experimental [ 2 ][ 12 ] |
| Resource Management | ||||||
| Cpupool advanced partitioning |
✓ | ✓ | ✓ | ✓ | ✓ | |
| Credit 2 Scheduler designed for latency-sensitive workloads and very large systems. |
✓prototype | ✓prototype | ✓experimental | ✓experimental | ✓experimental | |
| RTDS Based Scheduler Real-time CPU scheduler built to provide guaranteed CPU capacity to guest VMs on SMP hosts. |
✓experimental | |||||
| NUMA scheduler affinity | ✓ | ✓ | ✓ [ 12 ] | |||
| Scalability | ||||||
| 1GB/2MB super page support | ✓ | ✓ | ✓ | ✓ | ✓ | |
| Deliver events to PVHVM guests using Xen event channels | ✓ | ✓ | ✓ | ✓ | ✓ | |
| Interoperability / Hardware Support | ||||||
| X86 Nested Virtualisation Running a hypervisor inside an HVM guest |
✓experimental | ✓experimental | ✓preview | ✓preview [ 11 ] | ||
| HVM PXE Stack (x86) | gPXE | iPXE | iPXE | iPXE | iPXE | iPXE |
| Physical CPU Hotplug | ✓ | ✓ | ✓ | ✓ | ✓ | ✓[ 12 ] |
| Physical Memory Hotplug | ✓ | ✓ | ✓ | ✓ | ✓ | ✓[ 12 ] |
| Support for PV kernels in bzImage format | ✓ | ✓ | ✓ | ✓ | ✓ | ✓[ 12 ] |
| PCI Passthrough | ✓ | ✓ | ✓ | ✓ [ 12 ] | ✓ [ 12 ] | ✓ [ 12 ][ 13 ] |
| X86 Advanced Vector eXtension (AVX) | ✓ [ 4 ] | ✓ | ✓ | ✓ | ✓ | |
| X86 Cache Monitoring Technology (CMT) | ✓ preview | |||||
| High Availability and Fault Tolerance | ||||||
| Live Migration, Save & Restore | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ [ 12 ] |
| Remus Fault Tolerance | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ improvements for COLO [ 10 ][ 12 ] |
| X86 vMCE Forward Machine Check Exceptions to Appropriate guests |
✓ | ✓ | ✓ | ✓ | ||
| Network and Storage | ||||||
| Blktap2 | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| Online resize of virtual disks | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| Security (also see this presentation or this document) | ||||||
| Driver Domains | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| Device Model Stub Domains | ✓ | ✓ | ✓ | ✓ | ✓ | ✓[ 12 ] |
| Virtual Machine Introspection (Memaccess API) enabling integration of 3rd party security solutions into Xen virtualized environments |
✓ | ✓ | ✓ | ✓ | ✓ improvements[ 12 ] | |
| XSM & FLASK mandatory access control policy providing fine-grained controls over Xen domains, similar to SELinux |
✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| XSM & FLASK support for IS_PRIV | ✓ | ✓ | ✓ | |||
| vTPM Support |
✓ | ✓ | ✓ | ✓ updates and new functionality |
✓ | ✓ |
| Tooling | ||||||
| gdbsx debugger to debug ELF guests |
✓ | ✓ | ✓ | ✓ | ✓ | ✓[ 12 ] |
| vPMU Virtual Performance Management Unit for HVM guests |
✓ [ 4 ] | ✓ [ 4 ] | ✓ [ 4 ] | ✓ [ 4 ] | ✓ [ 4 ] | ✓ [ 4 ][ 12 ] |
| Serial console | ✓ | ✓ | ✓ | ✓Add EHCI debug support | ✓ | ✓Add Oxford PCIe, and Broadcom TrueManage support |
| xentrace performance analysis |
✓ | ✓ | ✓ | ✓ | ✓ | ✓[ 12 ] |
| 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 |
✓preview | ✓default, unless stubdomains are used | ✓default, unless stubdomains are used | ✓default, unless stubdomains are used | ||
| 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 ] | ✓experimental [ 4 ] | ||
| 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 |
✓ | ✓ | ✓ | ✓ | ||
[ 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.
