On 12/7/2009 7:24 AM, Diederick Stoffers wrote: > [root at localhost ~]# uname -a > Linux localhost.localdomain 2.6.18-164.6.1.el5xen #1 SMP Tue Nov 3 > 16:48:13 EST 2009 x86_64 x86_64 x86_64 GNU/Linux > If you dig back through the xen-users mailing list, there's a thread that discusses this recently. Look for a subject of "[Xen-users] Memory not seen in Dom0" back around Nov 8th. I tried to get GMane's web interface to toss up a direct link to the thread, but gave up. nntp://news.gmane.org/gmane.comp.emulators.xen.user Supposedly, it's not an issue unless you really really want >32GB in the Dom0 host. The Xen 64bit kernel (currently?) limits the Dom0 to 32GB. But any guest VMs that you create will initially use the RAM not used by the Dom0. Most folks recommend that you limit Dom0's memory usage in grub.conf (using the dom0_mem= argument). Or you can set it later using "xm mem-set 0 ###M".