Build Xen 4.1.2-rc1 for Ubuntu 11.10

$ hg clone -r 4.1.2-rc1 http://xenbits.xen.org/hg/xen-4.1-testing.hg/
$ cp -R xen-4.1-testing.hg xen-4.1.2~rc1
$ git clone git://xenbits.xensource.com/qemu-xen-4.1-testing.git qemu
$ tar -zcvf xen_4.1.2~rc1.orig-qemu.tar.gz ./qemu/*
$ tar -zcvf xen-4.1.2~rc1.tar.gz ./xen-4.1.2~rc1/*
$ cd xen-4.1.2~rc1
$ dh_make -e <email address hidden> -f ../xen-4.1.2~rc1.tar.gz
$ tar -zxvf ../xen_4.1.2~rc1.orig-qemu.tar.gz
$ cd ..
$ wget https://launchpad.net/ubuntu/+archive/primary/+files/xen_4.1.1-1ubuntu1.debian.tar.gz
$ tar -zxvf xen_4.1.1-1ubuntu1.debian.tar.gz
Update debian/patches/series
$ cp -R debian ./xen-4.1.2~rc1
Update changelog
$ debuild -sa -S -k'PGPKEY'

In fact debian folder you can get at http://packages.debian.org/source/sid/xen

root@boris-P5Q-E:~# xl info
host : boris-P5Q-E
release : 3.0.0-9-generic
version : #14-Ubuntu SMP Tue Aug 23 17:03:26 UTC 2011
machine : x86_64
nr_cpus : 2
nr_nodes : 1
cores_per_socket : 2
threads_per_core : 1
cpu_mhz : 2999
hw_caps : bfebfbff:20100800:00000000:00000940:0008e3fd:00000000:00000001:00000000
virt_caps : hvm
total_memory : 8191
free_memory : 1660
free_cpus : 0
xen_major : 4
xen_minor : 1
xen_extra : .2-rc1
xen_caps : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32 hvm-3.0-x86_32p hvm-3.0-x86_64
xen_scheduler : credit
xen_pagesize : 4096
platform_params : virt_start=0xffff800000000000
xen_changeset : unavailable
xen_commandline : placeholder
cc_compiler : gcc version 4.6.1 (Ubuntu/Linaro 4.6.1-7ubuntu2)
cc_compile_by : bderzhavets
cc_compile_domain : yahoo.com
cc_compile_date : Fri Aug 26 05:09:16 UTC 2011
xend_config_format : 4
root@boris-P5Q-E:~# virsh version
Compiled against library: libvir 0.9.2
Using library: libvir 0.9.2
Using API: Xen 3.0.1
Running hypervisor: Xen 4.1.0