I tried many ISO's and the systems that worked before I did a dist upgrade failed to boot also
I just tried it with 2 cpu's and 2GB of ram and it still failed.
I do not get to a point where I can get dmesg output but I have included a screenshot
I have reproduced this issue on a Dell R710, 2950 and R610.
I installed with the 11.04 Server ISO image.
Re-installing 10.10 server allowed the guests to boot as did dropping the vcpu number down to 1
Here are the ISO images I was using for the guests.
root@usmirror001:/export/isos/Operating_Systems/Linux# isoinfo -d -i CentOS-5.5-i386-bin-DVD.isoCD-ROM is in ISO 9660 formatSystem id: LINUXVolume id: CentOS_5.5_FinalVolume set id: Publisher id: CentOS ProjectData preparer id: CentOSApplication id: CentOS_5.5_FinalCopyright File id: Abstract File id: Bibliographic File id: Volume set size is: 1Volume set sequence number is: 1Logical block size is: 2048Volume size is: 2043515El Torito VD version 1 found, boot catalog is in sector 406Joliet with UCS level 3 foundRock Ridge signatures version 1 foundEltorito validation header:    Hid 1    Arch 0 (x86)    ID 'CentOS Project'    Key 55 AA    Eltorito defaultboot header:        Bootid 88 (bootable)        Boot media 0 (No Emulation Boot)        Load segment 0        Sys type 0        Nsect 4        Bootoff 197 407
root@usmirror001:/export/isos/Operating_Systems/Linux# isoinfo -d -i CentOS-5.6-i386-LiveCD.iso CD-ROM is in ISO 9660 formatSystem id: LINUXVolume id: CentOS-5.6-i386-LiveCDVolume set id: Publisher id: Data preparer id: Application id: MKISOFS ISO 9660/HFS FILESYSTEM BUILDER & CDRECORD CD-R/DVD CREATOR (C) 1993 E.YOUNGDALE (C) 1997 J.PEARSON/J.SCHILLINGCopyright File id: Abstract File id: Bibliographic File id: Volume set size is: 1Volume set sequence number is: 1Logical block size is: 2048Volume size is: 354800El Torito VD version 1 found, boot catalog is in sector 36Joliet with UCS level 3 foundRock Ridge signatures version 1 foundEltorito validation header:    Hid 1    Arch 0 (x86)    ID ''    Key 55 AA    Eltorito defaultboot header:        Bootid 88 (bootable)        Boot media 0 (No Emulation Boot)        Load segment 0        Sys type 0        Nsect 4        Bootoff 25 37



> Date: Thu, 23 Jun 2011 18:50:42 +0000
> From: <email address hidden>
> To: <email address hidden>
> Subject: [Bug 795717] Re: 32bit rhel and centos 5.(5|6) hangs on boot on natty
> 
> I tried to reproduce using the CentOS 5.5 netboot iso and also the live
> cd but did not get any crashes on initial boot.  I tried on a much
> smaller system, though, (2cpu 4G).
> 
> Were you using DVD image?
> 
> -- 
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/795717
> 
> Title:
>   32bit rhel and centos 5.(5|6) hangs on boot on natty
> 
> Status in “qemu-kvm” package in Ubuntu:
>   New
> 
> Bug description:
>   Binary package hint: qemu-kvm
> 
>   I have several guest images that ran fine under 10.10, RHEL and or
>   CENTOS 5.5 and 5.6 x86 all hang either from ISO or from disk image on
>   boot, some times it will find the LVM and mount and crash sometimes it
>   will crash after NASH starts.
> 
>   Description:	Ubuntu 11.04
>   Release:	11.04
> 
>   
>   root@usebskvm004:~# virsh version
>   Compiled against library: libvir 0.8.8
>   Using library: libvir 0.8.8
>   Using API: QEMU 0.8.8
>   Running hypervisor: QEMU 0.14.0
> 
> 
> 
>   Description:	Ubuntu 11.04
>   Release:	11.04
> 
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/ubuntu/+source/qemu-kvm/+bug/795717/+subscriptions