[TriLUG] >4 GB HIMEM Question

[James]

Mike,

  free:
               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
GB.

  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.

Thanks,
James

>
> 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