Re: Max ram for linux?

Walter Mautner wrote:

Michael Heiming enlightened us alt.linux-(ab)users with:

....
The 64 GB mentioned in this thread are just the limit for x86
hardware...

Damn. Got a hp bladeserver with a dual opteron,and 4G of ram.
When starting a 2.6.17 kernel (compiled for x64) without options, it
panicks at boot, with different messages.
When I give it a "mem=4000M" it starts just fine, but has only something
like 3.5G RAM available. We would like to expand memory even more, for
running vmware server machines.
Using a 32bit linux with appropriate kernel, no problem.
I cannot find any setting in the (flashed up-to-date) bios to disable
the memory remapping(?) of this dl360p4 box .... someone a cluestick?
On x86 type systems when you have 4 gig of ram installed, some of it will
HAVE to go above 4 gig or be lost. The reason is that the block from 4gig
down to about 3.3 gig is occupied by BIOS, IOxAPIC's, SMM, MMIO, MMCFG etc
You need a kernel that supports PAE (Physical Address Extensions) so you can
get above 4gig (assuming 32 bit mode). I believe it is now a kernel compile
option kernel so download a current kernel compile it for your
requirements. This also gives you the advantage of dumping stuff you don't
need, optimizing kernel and module code for you particular processor etc
Eric

.

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