I’ve recently installed a Debian Squeeze system with Xen4. Since the pretty new mix of Grub2 and Xen, I’ve had little problems finding around how to apply the dom0_mem option to boot command line.
To add the usual dom0 options to kernel command line, just edit /etc/defaults/grub and add a line as follows:
After that, obviously run update-grub.
It wasn’t very hard, but found no examples so far. 🙂