[rhn-users] Unable to boot with more than 4GB of RAM

[Doerbeck, Christoph]

Here's a snippet from some of my notes on PAE.  Just remember that your
hardware must also support PAE.
 
The 32bit architecture of the Intel x86 CPU has a limit of 4GB of
addressable memory. Servers which support Process Address Extension
(PAE) have a 36bit address space which supports up to 64GB of memory.
The RedHat 2.4.21 hugemem kernel supports PAE in addition to a memory
model called the 4/4 split (64GB of memory and a ~4GB single memory
segment). 
 

	-----Original Message-----
	From: Doerbeck, Christoph 
	Sent: Thursday, July 21, 2005 4:21 PM
	To: Red Hat Network Users List
	Subject: RE: [rhn-users] Unable to boot with more than 4GB of
RAM
	
	
	PAE is a hardware/software trick that allows a 32bit system to
address 36-bits of memory (If I recall correctly).  In any case, it
technically allows up to 64 Gigs of ram. However, it's not linear and is
broken into 3.2 (ish) gigabyte pages of memory that can be addressed by
a PAE enabled kernel.  Your hardware also has to support PAE (which I
would think your box does? What is your hardware?)
	 
	The ELsmp kernel in RHEL3 is PAE enabled, but I think it only
supports up to 16 GB of ram (maybe it's 32).
	You'll need to install the ELhugemem kernel to go higher.
	 
	Are you sure you are running ELsmp?  What does 'cat
/proc/meminfo' show?

		-----Original Message-----
		From: Mei.Zhang at alltel.com [mailto:Mei.Zhang at alltel.com]

		Sent: Thursday, July 21, 2005 3:06 PM
		To: rhn-users at redhat.com
		Subject: RE: [rhn-users] Unable to boot with more than
4GB of RAM
		
		
		You may need 64bit rhel

		what is PAE enabled kernel?        

			-----Original Message-----
			From: rhn-users-bounces at redhat.com
[mailto:rhn-users-bounces at redhat.com]On Behalf Of Serge Bianda
			Sent: Thursday, July 21, 2005 3:01 PM
			To: rhn-users at redhat.com
			Subject: [rhn-users] Unable to boot with more
than 4GB of RAM
			
			

			Hello,

			 

			I had three machines that we migrated from SuSE
9 to RHEL 3 ES, and Under SuSE the amount of memory was showing
correctly as 6GB, but under RHEL when I do a dmesg I get the following
report:

			 Warning only 4GB will be used.

			Use a PAE enabled kernel.

			 

			Any Ideay on how to resolve that and have RHEL
ustilize the maximum memory? I have the following kernel loaded:
2.4.21-27.ELsmp

			 

			Thanks

			 

			Serge

			 

	
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