invalid xen kernel in dom0 /boot/grub/grub.conf -- how can i fix it automatically?

[Joe Linoff]

Hi Folks:

When I provision my dom0 server using cobbler, it uses the wrong xen
kernel in the /boot/grub/grub.conf file which causes xend to fail with a
permissions problem. I can fix it manually but I would like to fix
automatically. There are at least two possible choices:

1) edit during the %post of kickstart or 
  2) configure the pxe templates (/etc/cobbler/pxe) correctly.

I think that I can manage the kickstart stuff but I do not know how to
fix the templates. Can someone help me with that or at least point me to
a reference? I didn't see anything detailed on the Trac site.

The problem and the fix are shown in detail below. The grub.conf files
are identical except for line 8.

Here is the broken grub.conf:

1 # BROKEN: it should be using /xen.gz-3.4.3 at line 8
   2 default=0
   3 timeout=5
   4 splashimage=(hd0,0)/grub/splash.xpm.gz
   5 hiddenmenu
   6 title CentOS (2.6.18-194.26.1.el5xen)
   7      root (hd0,0)
   8      kernel /xen.gz-2.6.18-194.26.1.el5
   9      module /vmlinuz-2.6.18-194.26.1.el5xen ro
root=/dev/VolGroup00/LogVol00
  10      module /initrd-2.6.18-194.26.1.el5xen.img
  11 title CentOS-base (2.6.18-194.26.1.el5)
  12      root (hd0,0)
  13      kernel /vmlinuz-2.6.18-194.26.1.el5 ro
root=/dev/VolGroup00/LogVol00
  14      initrd /initrd-2.6.18-194.26.1.el5.img

Here is the fixed grub.conf:

1 # FIXED: changed /xen.gz-2.6.18-194.26.1.el5 --> /xen.gz-3.4.3 at
line 8
   2 default=0
   3 timeout=5
   4 splashimage=(hd0,0)/grub/splash.xpm.gz
   5 hiddenmenu
   6 title CentOS (2.6.18-194.26.1.el5xen)
   7      root (hd0,0)
   8      kernel /xen.gz-3.4.3
   9      module /vmlinuz-2.6.18-194.26.1.el5xen ro
root=/dev/VolGroup00/LogVol00
  10      module /initrd-2.6.18-194.26.1.el5xen.img
  11 title CentOS-base (2.6.18-194.26.1.el5)
  12      root (hd0,0)
  13      kernel /vmlinuz-2.6.18-194.26.1.el5 ro
root=/dev/VolGroup00/LogVol00
  14      initrd /initrd-2.6.18-194.26.1.el5.img

Error message from /var/log/xen/xend.log:

[2011-01-05 13:54:00 6148] ERROR (SrvDaemon:349) Exception starting
xend ((13, 'Permission denied'))
  Traceback (most recent call last):
    File
"/usr/lib64/python2.4/site-packages/xen/xend/server/SrvDaemon.py", line
341, in run
      servers = SrvServer.create()
    File
"/usr/lib64/python2.4/site-packages/xen/xend/server/SrvServer.py", line
251, in create
      root.putChild('xend', SrvRoot())
    File
"/usr/lib64/python2.4/site-packages/xen/xend/server/SrvRoot.py", line
40, in __init__
      self.get(name)
    File "/usr/lib64/python2.4/site-packages/xen/web/SrvDir.py", line
84, in get
      val = val.getobj()
    File "/usr/lib64/python2.4/site-packages/xen/web/SrvDir.py", line
52, in getobj
      self.obj = klassobj()
    File
"/usr/lib64/python2.4/site-packages/xen/xend/server/SrvNode.py", line
30, in __init__
      self.xn = XendNode.instance()
    File "/usr/lib64/python2.4/site-packages/xen/xend/XendNode.py", line
948, in instance
      inst = XendNode()
    File "/usr/lib64/python2.4/site-packages/xen/xend/XendNode.py", line
91, in __init__
      self.other_config["xen_pagesize"] =
self.xeninfo_dict()["xen_pagesize"]
    File "/usr/lib64/python2.4/site-packages/xen/xend/XendNode.py", line
937, in xeninfo_dict
      return dict(self.xeninfo())
    File "/usr/lib64/python2.4/site-packages/xen/xend/XendNode.py", line
881, in xeninfo
      info['xen_scheduler'] = self.xenschedinfo()
    File "/usr/lib64/python2.4/site-packages/xen/xend/XendNode.py", line
871, in xenschedinfo
      sched_id = self.xc.sched_id_get()
  Error: (13, 'Permission denied')

Thanks,

Joe