Board index Linux FAQ's

Moderator: chandranjoy

How to enable more than 4GB RAM support on Linux 32bit OS?

Postby chandranjoy » Wed Jun 09, 2010 7:05 pm

Check your kernel version
# uname -r
2.6.18-8.1.3.el5


Then check whether your Server Processor(CPU) would support PAE(Physical Address Extension) or not.
cat /proc/cpuinfo |grep -i pae

Output as follows:
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht pni syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow pni
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht pni syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow pni


If your CPU doesn't support PAE please do not go ahead further steps and reinstall your OS with 64bit support.
# yum info kernel-PAE


Available Packages

Name : kernel-PAE

Summary: The Linux kernel compiled for PAE capable machines.

Description:

This package includes a version of the Linux kernel with support for up to
64GB of high memory. It requires a CPU with Physical Address Extensions (PAE).

The non-PAE kernel can only address up to 4GB of memory.

Install the kernel-PAE package if your machine has more than 4GB of memory.

# yum install kernel-PAE


Q:how do you enable the PAE kernel after you reboot?

A:Just install kernel-PAE and boot it. This kernel is PAE-enabled.


Ensure the followings:

cat /etc/sysconfig/kernel
# UPDATEDEFAULT specifies if new-kernel-pkg should make
# new kernels the default
UPDATEDEFAULT=yes

# DEFAULTKERNEL specifies the default kernel package type
DEFAULTKERNEL=kernel-PAE


After the server reboot PAE kernel will be enabled and it will automatically detect/handle more than 4GB of RAM.
chandranjoy
Site Admin
 
Posts: 283
Joined: Fri Oct 23, 2009 11:19 pm

Return to FAQ's

Who is online

Users browsing this forum: No registered users and 1 guest


cron