[TriLUG] >4 GB HIMEM Question
johnw at berningeronline.net
Wed Feb 2 13:34:43 EST 2005
Recompiling the kernel should work, but if you're using Red Hat (which I
think you are, tho my reading between the lines may be wrong), the
easier option is to use the -enterprise or -hugemem (on RHEL 2.1 and
RHEL 3 respectively) kernel. The i686 kernel will work just fine, even
on an AMD system.
On Wed, 02 Feb 2005, James wrote:
> total used free shared buffers cached
> Mem: 4009076 2400212 1608864 0 226400 1465612
> -/+ buffers/cache: 708200 3300876
> cat /proc/meminfo:
> total: used: free: shared: buffers: cached:
> Mem: 4105293824 2457948160 1647345664 0 231841792 1500786688
> MemTotal: 4009076 kB
> Trust me, it is only recognizing 4 GB. Which makes sense because you have
> to recompile the kernel with high memory support in order to access > 4
> My question, though, is if I can use the kernel high memory (> 4 GB)
> option with AMD64 processors?
> My understanding is that the feature that allows you to access 4 - 64 GB
> is one that exists in Intel chips, but I do not know if it exists in AMD
> chips. I could however, access all the RAM if I installed 64 bit Red
> Hat because the natural limit RAM limit of a 64 bit chip utilized by a
> 64 bit OS is 2^64 bytes opposed to the limit on a 32 bit chip, 2^32 or 4
> GB. The > 4 GB access is a hack, as far as I can tell.
> Please correct me if I'm wrong, I am certainly not an expert on processor
> or kernel architecture.
> > We've got a quad Xeon (which is 32bit) with 10GB of RAM using RHEL2.1.
> > Seems to be humming along just fine. What makes you think that it's not
> > using all of your memory?
> > Mike
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