Xen 4.3 Release Notes
Xen 4.3.0 is under development.
The default installation prefix has been changed to /usr/local. Previously the default installation prefix was /usr To restore the previous behaviour, specify --prefix=/usr when running ./configure, e.g.:
$ ./configure --prefix=/usr
If you choose to accept the new default then be sure to cleanup any residual bits of the old installation in the old prefix, especially libraries and tools which you might pick up by mistake.
Due to this change it may also now be necessary to run /sbin/ldconfig as root after installing Xen.