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Old 08-17-2009, 04:09 PM   #1
MikeQ
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High Memory Support


I have a 32bit CentOS System running CPanel with 4GB Ram. When I switch to 4GB I end up with 3.2G of ram. However, if I use the 64GB Option, I get my full 4. Is running the 64GB unsafe in a 32bit?
 
Old 08-17-2009, 05:09 PM   #2
Quakeboy02
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Quote:
Originally Posted by MikeQ View Post
I have a 32bit CentOS System running CPanel with 4GB Ram. When I switch to 4GB I end up with 3.2G of ram. However, if I use the 64GB Option, I get my full 4. Is running the 64GB unsafe in a 32bit?
That's normal. You're fine.
 
Old 08-17-2009, 08:19 PM   #3
sundialsvcs
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The 32-bit system kernels have limits as to the maximum amount of RAM that they can address. If presented with more than this, they'll ignore the extra.
 
Old 08-17-2009, 10:03 PM   #4
MikeQ
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So running the 64bit(64GB) which gives me my full 4GB is fine and safe?
 
Old 08-17-2009, 10:43 PM   #5
Quakeboy02
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The 64GB or HIGHMEM64GB is required to turn on PAE (Google is your friend) in the kernel. That's actually 36 address bits, I believe, and is done in the kernel. Your 32-bit program doesn't get access to 64GB of RAM, though. If you want to read more than I'm interested in, look at the wiki. Otherwise, move along - nothing to see here.
 
Old 08-18-2009, 11:38 AM   #6
vonbiber
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Here's an excerpt of kernel config:

CONFIG_X86_PAE=y
# CONFIG_NOHIGHMEM is not set
# CONFIG_HIGHMEM4G is not set
CONFIG_HIGHMEM64G=y
CONFIG_HIGHMEM=y
CONFIG_X86_32=y
# CONFIG_X86_64 is not set


I have 4GB of RAM. Before I rebuilt the kernel with
these options, only 3GB was detected.
 
Old 08-18-2009, 11:43 AM   #7
Quakeboy02
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Quote:
Originally Posted by vonbiber View Post
Here's an excerpt of kernel config:

CONFIG_X86_PAE=y
# CONFIG_NOHIGHMEM is not set
# CONFIG_HIGHMEM4G is not set
CONFIG_HIGHMEM64G=y
CONFIG_HIGHMEM=y
CONFIG_X86_32=y
# CONFIG_X86_64 is not set


I have 4GB of RAM. Before I rebuilt the kernel with
these options, only 3GB was detected.
Unless you are the original poster, then you should really open a new thread for this new question.
 
Old 08-19-2009, 04:51 AM   #8
vonbiber
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Quote:
Originally Posted by Quakeboy02 View Post
Unless you are the original poster, then you should really open a new thread for this new question.
I was trying to add this info for MikeQ
 
  


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