[CentOS] centos5/xen does not see all memory

Tue Jul 31 18:55:45 UTC 2007
Peter Peltonen <peter.peltonen at gmail.com>

I have a server with 6 gigs of memory. CentOS5/Xen sees only half of
it. Could someone advice me how to get it recognize all my memory?

I have installed 32bit CentOS5 and I'm running
kernel-xen-2.6.18-8.1.8.el5. This kernel should have PAE support:

$ grep PAE /boot/config-2.6.18-8.1.8.el5xen
CONFIG_X86_PAE=y

But xentop reports only 3 gigs of memory:

Mem: 3145148k total, 2400512k used, 744636k free    CPUs: 2 @ 2612MHz

If I boot with kernel-PAE-2.6.18-8.1.8.el5 the system recognizes all
memory but I cannot use Xen.

My motherboard is Supermicro H8SMA-2 A64/Opteron with MD Athlon 64 X2
5200+ processor
and 2 x 1GB ECC DDR-II SDRAM and 2x 2GB ECC DDR-II SDRAM.

Regards,
Peter