Xen 4.2 Release Notes

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Revision as of 12:14, 7 September 2012 by Ijc (talk | contribs) (Reference 4.2 feature list instead of duplicating.)
Icon Ambox.png This is a draft of the Xen 4.2 release notes. Xen 4.2 is not yet released.


New Features

Xen 4.2 contains many new features and improvements to existing functionality. Changes include improvements to Security, Scalability, Performance, RAS, Documentation and to the toolstack.

For a list of new features and changes see Xen 4.2 Feature List.

Default Toolstack

XL is now the default toolstack supplied with Xen. Please see the XL page for guidance on migrating from Xend.

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).

As a consequence of this change Xen now defaults to installing libraries into /usr/lib by default. Users on systems which use /usr/lib64 for 64-bit libraries should use the --libdir option. e.g:

$ ./configure --libdir=/usr/lib64

Known issues

XL's default configuration is not compatible with driver domains. To use driver domains with XL you should set run_hotplug_scripts=0 in /etc/xen/xl.conf.

On systems running a 32-bit hypervisor xl info will report incorrectly report large values for sharing_used_memory and sharing_freed_memory. Memory sharing is not supported on the 32-bit hypervisor and these should read zero.