Hello, 
I've downloaded the xen 4.0.1 version as it is explained here:
So, I've made a clone from repository, with the following command:
 
So, I am able to boot dom0 successfully, but apparently xend its not starting.
A few things that I have noticed: 
1) lsmod does not list evtchn and neither gntdev, and they are not compiled as a Module. I have tried also to insert them with lsmod, and of course, I dont have them.
2) The nodes appear in both /proc/misc and /dev/xen, and the numbers are correct
% cat /proc/misc 
 52 freefall
224 tpm0
 53 network_throughput
 54 network_latency
 55 cpu_dma_latency
 56 device-mapper
  1 psaux
200 tun
 57 pktcdvd
228 hpet
 58 blktap-control
 59 xen/gntdev
 60 xen/evtchn
229 fuse
 61 ecryptfs
231 snapshot
227 mcelog
 62 rfkill
 63 vga_arbiter
% ll /dev/xen 
total 0
crw-rw---- 1 root root 10, 60 2010-10-27 17:32 evtchn
crw-rw---- 1 root root 10, 59 2010-10-27 17:32 gntdev
 
3) I am really running dom)
% cat /proc/xen/capabilities   
control_d
4) /var/log/xen shows the following errors:
xend.log
[2010-10-27 17:32:31 1307] INFO (SrvDaemon:331) Xend Daemon started
[2010-10-27 17:32:31 1307] INFO (SrvDaemon:335) Xend changeset: Wed Aug 25 09:22:42 2010 +0100 21324:b536ebfba183.
[2010-10-27 17:32:31 1307] ERROR (SrvDaemon:347) Exception starting xend ((13, 'Permission denied'))
Traceback (most recent call last):
  File "/usr/lib/python2.6/dist-packages/xen/xend/server/SrvDaemon.py", line 339, in run
    servers = SrvServer.create()
  File "/usr/lib/python2.6/dist-packages/xen/xend/server/SrvServer.py", line 251, in create
    root.putChild('xend', SrvRoot())
  File "/usr/lib/python2.6/dist-packages/xen/xend/server/SrvRoot.py", line 40, in __init__
    self.get(name)
  File "/usr/lib/python2.6/dist-packages/xen/web/SrvDir.py", line 82, in get
    val = val.getobj()
  File "/usr/lib/python2.6/dist-packages/xen/web/SrvDir.py", line 52, in getobj
    self.obj = klassobj()
  File "/usr/lib/python2.6/dist-packages/xen/xend/server/SrvNode.py", line 30, in __init__
    self.xn = XendNode.instance()
  File "/usr/lib/python2.6/dist-packages/xen/xend/XendNode.py", line 752, in instance
    inst = XendNode()
  File "/usr/lib/python2.6/dist-packages/xen/xend/XendNode.py", line 87, in __init__
    self.other_config["xen_pagesize"] = self.xeninfo_dict()["xen_pagesize"]
  File "/usr/lib/python2.6/dist-packages/xen/xend/XendNode.py", line 741, in xeninfo_dict
    return dict(self.xeninfo())
  File "/usr/lib/python2.6/dist-packages/xen/xend/XendNode.py", line 685, in xeninfo
    info['xen_scheduler'] = self.xenschedinfo()
  File "/usr/lib/python2.6/dist-packages/xen/xend/XendNode.py", line 675, in xenschedinfo
    sched_id = self.xc.sched_id_get()
Error: (13, 'Permission denied')
xend-debug.log
Xend started at Wed Oct 27 17:32:31 2010.
domctl operation failed -- need to rebuild the user-space tool set?
sysctl operation failed -- need to rebuild the user-space tool set?
Exception starting xend: (13, 'Permission denied')
Exception in thread Thread-2:
Traceback (most recent call last):
  File "/usr/lib/python2.6/threading.py", line 532, in __bootstrap_inner
    self.run()
  File "/usr/lib/python2.6/dist-packages/xen/xend/XendMonitor.py", line 230, in run
    for domid, cputimes in self._get_cpu_stats().items():
  File "/usr/lib/python2.6/dist-packages/xen/xend/XendMonitor.py", line 208, in _get_cpu_stats
    for domain in self.xc.domain_getinfo():
Error: (13, 'Permission denied')
Does anyone have any Idea of how can I start xend correctly ?
Thank you!
--
David Cemin