Most poeple get confused when it comes to configuring kdump for dom0. Since there are two entries in grub.conf, one representing the hypervisor and the other representing the dom0 kernel, the confusion is while thinking where should one give the "crashkernel" parameter. Have seen some people who are not ready to do trial and error passing the "crashkernel" parameter to both hypervisor and kernel. If you are too lazy to do a trial and error, this blog may help you.
The crashkernel parameter need to be passed to the hypervisor.
Eg, (Taken from my test system)
title Red Hat Enterprise Linux Server (2.6.18-92.1.18.el5xen)
kernel /xen.gz-2.6.18-92.1.18.el5 crashkernel=128M@16M
module /vmlinuz-2.6.18-92.1.18.el5xen ro root=/dev/VolGroup00/LogVol00 rhgb quiet
- Configure /etc/kdump.conf appropriately. The file is self descriptive.
- Run "service kdump propagate"
- Run "service kdump start"