[Beowulf] 64 bit Xeons?

[Chris Samuel]

On Tue, 18 Jan 2005 03:47 am, Craig Tierney wrote:

> It uses the 64-bit extensions that AMD uses for the Opteron.

I believe that Intel tinkered with a couple of the instructions of the 
original AMD instruction set, so whilst it's almost identical it's not quite.

The major one that I'm aware of is that although it reports it supports an 
address size of 40 bits it can only handle 36 bits of physical memory.

There's more information on differences here:

http://www.ussg.iu.edu/hypermail/linux/kernel/0402.3/0276.html

also here:

http://www.redhat.com/docs/manuals/enterprise/RHEL-3-Manual/release-notes/as-amd64/RELEASE-NOTES-U2-x86_64-en.html#id3938207

and here:

http://www.extremetech.com/article2/0,3973,1561875,00.asp?kc=ETRSS02129TX1K0000532

cheers,
Chris
-- 
 Christopher Samuel - (03)9925 4751 - VPAC Systems & Network Admin
 Victorian Partnership for Advanced Computing http://www.vpac.org/
 Bldg 91, 110 Victoria Street, Carlton South, VIC 3053, Australia

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