Description of problem:
After i updated the server with the latest updates including 2.6.20-2931.fc7xen
and libvirt-0.3.2-1.fc7, all existing windows guest domains doesn't start
anymore and i can't install new windows guest domains.
A F7 x86_64 guest domains is running fine.


Version-Release number of selected component (if applicable):
2.6.20-2931.fc7xen


How reproducible:
always


Steps to Reproduce:
1. boot
2.
3.
  
Actual results:
Windows guest domains don't start and it is not possible to install new windows
domains.


Expected results:
Start a windows guest domain


Additional info:

[thomas srv1 ~]$ sudo virt-install -d -n sbs -r 512 --vcpus=1 -f
/dev/VolGroup01/sbs -w bridge:virbr0 --vnc -k DE -v --arch=i386
--os-type=windows --os-variant=win2k3 -c /var/www/html/install/SBS2003R2DE_DVD.iso

Mon, 10 Sep 2007 20:38:28 DEBUG Path is block file: Assuming Block disk type.
Disk /dev/VolGroup01/sbs is already in use by another guest! Do you really want
to use the disk (yes or no)? y


Starting install...
libvir: Xen Daemon error : GET operation failed:
libvir: Xen Daemon error : GET operation failed:
Mon, 10 Sep 2007 20:38:31 DEBUG    Creating guest from '<domain type='xen'>
  <name>sbs</name>
  <currentMemory>524288</currentMemory>
  <memory>524288</memory>
  <uuid>5f73764f-897c-401c-e9e5-17cb21333334</uuid>
  <os>
    <type arch='i386'>hvm</type>
    <loader>/usr/lib/xen/boot/hvmloader</loader>
    <boot dev='cdrom'/>
  </os>
  <features>
    <apic/><acpi/><pae/>
  </features>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>destroy</on_reboot>
  <on_crash>destroy</on_crash>
  <vcpu>1</vcpu>
  <devices>
    <emulator>/usr/lib64/xen/bin/qemu-dm</emulator>
    <console device='pty'/>
    <disk type='block' device='disk'>
      <source dev='/dev/VolGroup01/sbs'/>
      <target dev='hda'/>
    </disk>
    <disk type='file' device='cdrom'>
      <source file='/var/www/html/install/SBS2003R2DE_DVD.iso'/>
      <target dev='hdc'/>
      <readonly/>
    </disk>

    <interface type='bridge'>
      <source bridge='virbr0'/>
      <mac address='00:16:3e:33:eb:7b'/>
    </interface>

    <graphics type='vnc' port='-1' keymap='DE' />
  </devices>
</domain>
'

libvir: Xen Daemon error : POST operation failed: (xend.err "Error creating
domain: (12, 'Cannot allocate memory')") virDomainCreateLinux() failed POST
operation failed: (xend.err "Error creating domain: (12, 'Cannot allocate memory')")

Domain installation may not have been
 successful.  If it was, you can restart your domain
 by running 'virsh start sbs'; otherwise, please
 restart your installation.

Mon, 10 Sep 2007 20:38:31 ERROR virDomainCreateLinux() failed POST operation
failed: (xend.err "Error creating domain: (12, 'Cannot allocate memory')")

Traceback (most recent call last):
  File "/usr/bin/virt-install", line 474, in <module>
    main()
  File "/usr/bin/virt-install", line 438, in main
    dom = guest.start_install(conscb,progresscb)

File "/usr/lib/python2.5/site-packages/virtinst/Guest.py", line 710, in
start_install

    return self._do_install(consolecb, meter)

File "/usr/lib/python2.5/site-packages/virtinst/Guest.py", line 727, in _do_install

    self.domain = self.conn.createLinux(install_xml, 0)

File "/usr/lib64/python2.5/site-packages/libvirt.py", line 563, in createLinux
if ret is None:raise libvirtError('virDomainCreateLinux() failed', conn=self)
libvirtError: virDomainCreateLinux() failed POST operation failed: (xend.err
"Error creating domain: (12, 'Cannot allocate memory')")



[thomas srv1 ~]$ free
           total       used       free     shared    buffers     cached
Mem:       6154240    1312276    4841964          0     144660     600632
-/+ buffers/cache:     566984    5587256
Swap:      8323064          0    832306



Richard W.M. Jones thinks it he already has seen this and think it is a xen bug.
https://www.redhat.com/archives/libvir-list/2007-September/msg00049.html