How to limit xen dom0 RAM to a certain amount?
When there was grub1 and a grub.cfg, I knew how, just add to the kernel options there.
Now I have no clue. I have tried setting
GRUB_CMDLINE_LINUX_DEFAULT="nomodeset dom0_mem=640M,max:640M" in /etc/default/grub but no effect, dom0 still uses all RAM.