一、内核内存配置检查：
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可以通过以下办法来查看启动时内核是否支持64G内存
首先要弄清启动时用的是哪个内核
[root@study ~]# cat /boot/grub/grub.conf
...
default=0 （说明第一个条目是默认的启动）
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
root (hd0,0)
kernel /vmlinuz-2.6.9-34.ELsmp ro root=/dev/VolGroup00/LogVol00 rhgb quiet
initrd /initrd-2.6.9-34.ELsmp.img
title Red Hat Enterprise Linux AS-up (2.6.9-34.EL)
root (hd0,0)
kernel /vmlinuz-2.6.9-34.EL ro root=/dev/VolGroup00/LogVol00 rhgb quiet
initrd /initrd-2.6.9-34.EL.img
我的内核是vmlinuz-2.6.9-34.ELsmp
对应安装时的内核编译文件就是
/boot/config-2.6.9-34.ELsmp
检查高内存支持
[root@study ~]# more /boot/config-2.6.9-34.ELsmp |grep 4G
# CONFIG_X86_4G is not set
# CONFIG_X86_4G_VM_LAYOUT is not set
# CONFIG_HIGHMEM4G is not set
CONFIG_HIGHMEM64G=y 说明我的内核编译时选择了64G内存支持，
只有4G支持的情况会类似：
[root@study ~]# more /boot/config-2.6.9-34.EL |grep 4G
# CONFIG_X86_4G is not set
# CONFIG_X86_4G_VM_LAYOUT is not set
CONFIG_HIGHMEM4G=y
# CONFIG_HIGHMEM64G is not set