Xen 4.2 Release Notes

This is a draft of the Xen 4.2 release notes. Xen 4.2 is not yet released.

New Features

High level features include:

• Security:
  • Support for Intel Supervisor Mode Execution Protection
  • (Xen Security Modules) XSM / Flask improvements
• Scalability:
  • increased VM density for VDI use-cases
  • up to 256 Host CPUs for 64 bit HV
  • Multiple PCI segment support
  • Prefer oxenstored when present
• Performance
  • PCI pass-through for Linux Guests
  • AMD SVM DecodeAssist support
  • Remus memory image compression
• EFI support
• Libvchan cross domain comms in Xen mainline
• XL improvements, XEND is formally deprecated
• Documentation improvements (e.g. man pages)
• RAS:
  • Enhanced MCA support to include more failure types
  • APEI support (ACPI Platform Error Interface)

A more complete list of new features and changes is available at Xen 4.2

Default Toolstack

XL is now the default toolstack supplied with Xen. Please see MigrationGuideToXen4.1 for existing guidance on migrating from Xend to XL.

The previous Xend toolstack is now formally deprecated and should be expected to be removed in the 4.3 timescale. Therefore it is strongly recommended that users evaluate Xen 4.2 with XL for their use case and report any omissions or blockers such that they can be addressed for 4.3.

Build Requirements

The requirements for building Xen are documented in the README file in the Xen source tree.

Some additional build dependencies have been added since Xen 4.1:

• libyajl
• glib
• pkg-config
• markdown (optional)

In addition Xen will now prefer to use the system wide libaio if it is available. If libaio is not installed then an intree version will be used. Users are strongly encouraged to install their distribution's version of libaio.

An additional step has also been added to the build process. It is now necessary to run:

$ ./configure

before building the tools (e.g. make tools, make world, make dist etc).