How to get xen whole-machine dump image and analyse it prepair

civilvar

enable kexec

• apply kexec patches to xen source tree.   latest patches are available in xen-devel list.  (It maybe merged into xen 3.0.3)
  

install dom0cut

• 
  prerequirement: libelf, python, binutils
  get dom0cut script and libelf wrapper from http://people.valinux.co.jp/~moriwaka/dumpread/ install libelf wrapper
  
  $ wget http://people.valinux.co.jp/~moriwaka/dumpread/libelf-0.3.0.tar.gz
  $ tar zxf libelf-0.3.0.tar.gz
  $ cd libelf-0.3.0
  $ sudo python ./setup.py install
  
  install dom0cut script  
  $ wget http://people.valinux.co.jp/~moriwaka/dumpread/dumpread-20060927.tar.gz
  $ tar zxvf dumpread-20060927.tar.gz
  
  
  

prepair xen-syms, vmlinux

• 
  copy xen executable binary with symbols (when you compile, it is made at xen/xen-syms) and vmlinux used for domain 0
  
  

get coredump




load kdump kernel


1. append followings to xen boot args

• 
  kdump_megabytes=64 kdump_megabytes_base=32
  
  
  

2. on dom0, load kdump kernel, take a dump.

• 
  This is same as linux kdump usage. http://lse.sourceforge.net/kdump/
  
  

get a dump image

• 
  echo c > /proc/sysrq-trigger
  
  
  

after reboot, copy /proc/vmcore to core file.

• 
  cp /proc/vmcore /vmcore
  
  
  

analysis


Now dom0cut script eats large memory(about 100-200MB).  You should reboot machine before analysis.


extract domain 0 image

• 
  $ cd dumpread
  $ ./dom0cut_x86.py -d/vmcore --target=0 -odom0image -xxen-syms -txen
  
  
  

you maybe need LD_PRELOAD=/usr/local/lib/libelf.so to resolve conflict for distribution's libelf.(same-name different library is contained in Fedora Core or Redhat)


use crash

• 
  $ crash vmlinux dom0image
  
  
  

extract xen hypervisor image

• 
  $ cd dumpread
  $ ./dom0cut_x86.py -d/vmcore --target=x -oxenimage -xxen-syms -telf
  
  
  

use gdb


$ gdb xen-syms xenimage