Re: AMD Athlon64 X2 Dual-core and 4GB

From: Vladimir Lazarenko
Date: Fri Oct 28 2005 - 16:28:06 EST


If you want to use 4GB in 32 bit mode, you *need* remapping (or you lose
part of your memory). Remapping means you have MORE than 4 GB of physical
address, which means you need PAE to use it at all.

Yes, and PAE works fine with a 32bit kernel. I agree it is a silly
configuration and a 64bit kernel would use the memory more
efficiently. My basic point was that a dual-core is a recent enough
processor from AMD that it supports memory remapping. So with a
correct BIOS there should be no problems.


Earlier Opterons had remapping, too, just at the chip-select level. Even
with remapping, the memory that gets remapped gets mapped above 4 GB, so a
32 bit kernel still needs PAE to address it.

Well, my BIOS had 2 types of re-mapping, H/W and S/W, i enabled H/W remapping, compiled kernel with 64G HIGHMEM, and voila:

vlad@anarxi:~$ free
total used free shared buffers cached
Mem: 4151876 2972968 1178908 0 179008 679016
-/+ buffers/cache: 2114944 2036932


Thanks everyone!

Vladimir

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