[Leaplist] Only seeing 3G memory

[Bryan J. Smith]

From: Hank Lambert <hank at hanklambert.com>
> Subject: Re: [Leaplist] Only seeing 3G memory
> To: "This is the Leap Main List" <leaplist at leap-cf.org>
> Date: Tuesday, October 7, 2008, 7:42 PM
> Is it an Intel motherboard? Certain Intel motherboards have
> an issue where they only see 3 - 3.5 GB when you have 4 GB
> installed.

Many first-gen boards for AMD64 did as well.  They do not
setup the chipset and/or trace the address lines correctly
to allow paging them in beyond the 4GiB range.

I've just started to see a similar issue at 64GiB as well.
For Intel, it's a physical limit at 36-bit/64GiB -- sans new,
select Xeon 5000 series, which can now do 38-bit/256GiB.
For AMD, it's the board, as all original AMD64 always did
40-bit/1TiB, and new ones support up to 48-bit/256TiB.

For x86-64, the hard, physical limit of paging is
52-bit/4PiB.  There might be implementation issues above
48-bit/256TiB, at least if i686 programs are to run on it.


-- 
Bryan J Smith        Professional, Technical Annoyance
b.j.smith at ieee.org  http://www.linkedin.com/in/bjsmith
------------------------------------------------------
I'm a PC, but Linux -- Windows: Life Without Firewalls




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