centos 5 x86_64 32G内存限制

bios认出96G内存，系统启动后只能识别32G

The Red Hat Enterprise Linux Virtualization kernel does not support more than 32GB of memory for x86_64 systems. If you need to boot the virtualization kernel on systems with more than 32GB of physical memory installed, you must you must append the kernel command line with mem=32G. This example shows how to enable the proper parameters in the grub.conf file:

title Red Hat Enterprise Linux Server (2.6.18-4.elxen) root (hd0, 0) kernel /xen.gz-2.6.18-4-el5 mem=32G module /vmlinuz -2.6.18-4.el5xen ro root=LABEL=/ module /initrd-2.6.18-4.el5xen.img