====== Upgrade_domU_to_Lenny ======

Debian Lenny (version 5) was released on the 14th of Feb, 2009.

I decided to upgrade one of my domU's to Lenny to see how the dist-upgrade went.
 apt-get dist-upgrade

A nice email was sent to root with all the changes. There were a few questions about restarting services, and selecting which default configs to keep.

====== Kernel Error: 4gb seg fixup ======
Anyways, after I dist-upgraded, I got a whole load of kernel error messages:

 Feb 15 18:18:03 twister kernel: printk: 694 messages suppressed.
 Feb 15 18:18:03 twister kernel: 4gb seg fixup, process python (pid 1618), cs:ip 73:b7dff870
 Feb 15 18:18:08 twister kernel: printk: 696 messages suppressed.
 Feb 15 18:19:03 twister kernel: printk: 693 messages suppressed.
 Feb 15 18:19:03 twister kernel: 4gb seg fixup, process snmpd (pid 1657), cs:ip 73:b7bf71b4
 Feb 15 18:19:08 twister kernel: printk: 695 messages suppressed.
 Feb 15 18:19:08 twister kernel: 4gb seg fixup, process snmpd (pid 1657), cs:ip 73:b7bf71b4

These appeared for various running daemons.

====== Reasons for 4gb seg fixup ======
  * DomU was running Debian Lenny.
  * The DomU while running Lenny was using a Debian Etch Kernel on dom0
  * Solution 1: Upgrade dom0 to Debian Lenny, and thus dom0 would be using a correct kernel.
  * Solution 2: See below:

====== Solution to 4gb seg fixup on DomU Xen ======
 #On the domU
 apt-get install libc6-xen  (should already be installed)
 mv /lib/tls /lib/tls.disabled (should already be done)
 vi /etc/ld.so.conf.d/libc6-xen.conf
 #change "hwcap 1 nosegneg" to "hwcap 0 nosegneg"
 ldconfig
 reboot

====== Edit to 4gb seg fixup ======
After dis-upgrading lenny on another domU, after closer watching of the upgrade process, there was one step relating to this issue which I may have overlooked. The step was:
 Setting up libc6-xen (2.7-18) ...
 
 Configuration file `/etc/ld.so.conf.d/libc6-xen.conf'
  ==> File on system created by you or by a script.
  ==> File also in package provided by package maintainer.
    What would you like to do about it ?  Your options are:
     Y or I  : install the package maintainer's version
     N or O  : keep your currently-installed version
       D     : show the differences between the versions
       Z     : background this process to examine the situation
  The default action is to keep your current version.
 *** libc6-xen.conf (Y/I/N/O/D/Z) [[default=N]] ? D
 --- /etc/ld.so.conf.d/libc6-xen.conf    2007-04-20 17:34:58.000000000 +0100
 +++ /etc/ld.so.conf.d/libc6-xen.conf.dpkg-new   2009-01-04 18:12:21.000000000 +0000
 @@ -1 +1,6 @@
 -hwcap 0 nosegneg
 +# This directive teaches ldconfig to search in nosegneg subdirectories
 +# and cache the DSOs there with extra bit 1 set in their hwcap match
 +# fields. In Xen guest kernels, the vDSO tells the dynamic linker to
 +# search in nosegneg subdirectories and to match this extra hwcap bit
 +# in the ld.so.cache file.
 +hwcap 1 nosegneg

So, simply by choosing the default option, the correct entry gets added to /etc/ld.so.conf.d/libc6-xen.conf! I did do a reboot of the VM, and there were no 4gb seg fixup errors :-) All in all, on my second domU upgrade to lenny, there were no errors at all at all. Good Job Debian.

-----
http://www.completefusion.com/wordpress/4gb-seg-fixup-errors-on-debian-lenny-xen-domu/

http://www.nabble.com/Bug-499366:-%224gb-seg-fixup%22-not-fixed-in-2.7-14--td19972026.html

http://blog.kabisa.nl/2009/01/30/4gb-seg-fixup-errors-on-debian-lenny-xen-domu/

http://lists.xensource.com/archives/html/xen-users/2006-11/msg00026.html