This document describes the support status and in particular the security support status of the Xen branch within which you find it.
See the bottom of the file for the definitions of the support status levels etc.
Xen-Version: 4.10-unstable
Initial-Release: n/a
Supported-Until: TBD
Security-Support-Until: Unreleased - not yet security-supported
Status: Supported
[XXX Are there any restrictions (e.g. unsupported HW platforms that were not out at the time we released a version of Xen)?]
Status: Supported
[XXX Are there any restrictions (e.g. unsupported HW platforms that were not out at the time we released a version of Xen)?]
Status: Supported
[XXX Are there any restrictions (e.g. unsupported HW platforms that were not out at the time we released a version of Xen)?]
Status: Supported
Traditional Xen Project PV guest
Status: Supported
Fully virtualised guest using hardware virtualisation extensions
Requires hardware virtualisation support
Status: Supported
Fully virtualised guest using PV extensions/drivers for improved performance
Requires hardware virtualisation support
Status: Experimental
PVHv2
Requires hardware virtualisation support
[XXX Downgraded in 4.9 from preview to experimental when PVHv1 was removed and PVHv2 was added.]
Status: Supported
Limit-Security: 4095
Limit: 4095
May not work/boot ... but still should provide security support
Limit-Security: 16TB
Limit: 16TB
ACTION: Andy to suggest what this should say
Limit-Security: 8 for 32bit; 128 for 64bit
Limit: 8 for 32bit; 128 for 64bit
Limit-Security: 16GB for 32bit, 5TB for 64bit
Limit: 16GB for 32bit, 5TB for 64bit
Limit-Security: 512
Limit: 512
Limit-Security: >1TB
Limit: >1TB
Limit-Security: 128
Limit: 128
Limit-Security: 1TB
Limit: 1TB
Limit-Security: 8 for 32bit; 128 for 64bit
Limit: 8 for 32bit; 128 for 64bit
Limit-Security: 1TB
Limit: 1TB
[XXX Limited by supported host memory]
Limit-Security: 131072
Limit: 131072
Status: Supported
[XXX For man pages, see http://xenbits.xen.org/docs/unstable/man/xl.1.html]
Status: Supported
[XXX Used as a fallback if blkback and/or blktap2 are not available]
Status: Supported
[XXX See https://wiki.xenproject.org/wiki/XenNetworking#OpenvSwitch]
Status: Supported
Status: Preview
Status: Supported
Status: Supported
Status: Supported
Status: Supported
Status: Supported
Status: Supported
[XXX No security support for the xl libvirt driver from the Xen Project. For security support see https://libvirt.org/securityprocess.html]
Status: Supported
Debugger to debug ELF guests
[XXX Not yet supported on ARM.
Should there be security support?]
Status: Supported
Virtual Performance Management Unit for HVM guests
[XXX Not yet supported on ARM. Disabled by default (enable with hypervisor command line option). This feature is not security supported: see http://xenbits.xen.org/xsa/advisory-163.html]
Status: Supported
Logs key hypervisor and Dom0 kernel events to a file
[XXX Should there be security support?]
Status: Supported
Tool to capture Xen trace buffer data
[XXX Should there be security support?]
Status: Supported
[XXX Should there be security support?]
Status: Supported
Status: Preview
Allow sharing of identical pages between HVM guests
Status: Preview
Allow pages belonging to HVM guests to be paged to disk
Status: Experimental
Status: Preview
Allows external monitoring of hypervisor memory using Intel EPT by allowing to maintain multiple physical memory to machine physical mappings
[XXX Should there be security support?]
Status: Supported
Groups physical cpus into distinct groups called "cpupools", with each pool having the capability of using different schedulers and scheduling properties.
Status: Supported
The default scheduler, which is a weighted proportional fair share virtual CPU scheduler.
Status: Supported
Credit2 is a general purpose scheduler for Xen, designed with particular focus on fairness, responsiveness and scalability
Status: Experimental
A soft real-time CPU scheduler built to provide guaranteed CPU capacity to guest VMs on SMP hosts
Status: Supported
A periodically repeating fixed timeslice scheduler. Multicore support is not yet implemented.
[XXX Multicore support is not yet implemented.]
Status: Experimental
A very simple, very static scheduling posicy that always schedules the same vCPU(s) on the same pCPU(s). It is designed for maximum determinism and minimum overhead on embedded platforms.
Status: Supported
Enables Numa aware scheduling in Xen
[XXX Not yet supported on ARM.]
Status: Supported
Status: Supported
Status: Supported
Status: Supported
Status: Experimental
Status: Experimental
Status: Supported
Forward Machine Check Exceptions to Appropriate guests
Status: Supported
Status: Supported
Status: Obsolete
Status: Supported
Status: Supported
Status: Supported
Status: Supported
Vulnerabilities of a device model stub domain to a hostile driver domain are excluded from security support.
Status: Experimental
Status: Supported
For x86 only
[XXX Compile time disabled]
Status: Supported
Status: Experimental
[XXX Compile time disabled]
Status: Experimental
[XXX Compile time disabled]
Status: Supported
Status: ???
TXT-based integrity system for the Linux kernel and Xen hypervisor
Status: Experimental
Running a hypervisor inside an HVM guest
Status: Insecure
[XXX Via iPXE]
Status: Supported
Status: Supported
Status: Supported
Status: Insecure
[XXX Security support?]
Status: Supported
Status: Supported
Status: Preview
This file contains prose, and machine-readable fragments. The data in a machine-readable fragment relate to the section and subection in which it is fine.
The file is in markdown format. The machine-readable fragments are markdown literals containing RFC-822-like (deb822-like) data.
This gives the overall status of the feature, including security support status, functional completeness, etc. Refer to the detailed definitions below.
This is a summary of any restrictions which apply, particularly to functional or security support.
Full details of restrictions may be provided in the prose section of the feature entry, if a Restrictions tag is present.
For size limits. This figure shows the largest configuration which will receive security support. This does not mean that such a configuration will actually work.
This figure shows a theoretical size limit. This does not mean that such a large configuration will actually work.
Each Status value corresponds to levels of security support, testing, stability, etc., as follows:
Functional completeness: No
Functional stability: Here be dragons
Interface stability: Not stable
Security supported: No
Functional completeness: Yes
Functional stability: Quirky
Interface stability: Provisionally stable
Security supported: No
Functional completeness: Yes
Functional stability: Normal
Interface stability: Yes
Security supported: Yes
Functional completeness: Yes
Functional stability: Quirky
Interface stability: No (as in, may disappear the next release)
Security supported: Yes
All of these may appear in modified form. There are several interfaces, for instance, which are officially declared as not stable; in such a case this feature may be described as "Stable / Interface not stable".
Does it behave like a fully functional feature? Does it work on all expected platforms, or does it only work for a very specific sub-case? Does it have a sensible UI, or do you have to have a deep understanding of the internals to get it to work properly?
What is the risk of it exhibiting bugs?
General answers to the above:
Here be dragons
Pretty likely to still crash / fail to work. Not recommended unless you like life on the bleeding edge.
Quirky
Mostly works but may have odd behavior here and there. Recommended for playing around or for non-production use cases.
Normal
Ready for production use
If I build a system based on the current interfaces, will they still work when I upgrade to the next version?
Not stable
Interface is still in the early stages and still fairly likely to be broken in future updates.
Provisionally stable
We're not yet promising backwards compatibility, but we think this is probably the final form of the interface. It may still require some tweaks.
Stable
We will try very hard to avoid breaking backwards compatibility, and to fix any regressions that are reported.
Will XSAs be issued if security-related bugs are discovered in the functionality?
If "no", anyone who finds a security-related bug in the feature will be advised to post it publicly to the Xen Project mailing lists (or contact another security response team, if a relevant one exists).
Bugs found after the end of Security-Support-Until in the Release Support section will receive an XSA if they also affect newer, security-supported, versions of Xen. However, the Xen Project will not provide official fixes for non-security-supported versions.
Not all features interact well with all other features. Some features are only for HVM guests; some don't work with migration, &c.