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From Christopher Schultz <ch...@christopherschultz.net>
Subject Re: [OT]RE: Maximum memory that can be assigned to Tomcat on windows platform
Date Fri, 02 Dec 2011 01:32:13 GMT
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Casper,

On 12/1/11 3:39 AM, Casper Wandahl Schmidt wrote:
> Aha so I learned something new today :) I'm still puzzled as to
> how a 32 bit CPU can compute and fetch a memory cell with address
> above 4GB since it cannot hold this large value.

OS != CPU

Also, OS != process

While the chips and OSs are officially 32-bit, both are able to handle
integers that don't fit into 32-bit registers in various ways. Usually,
CPUs have registers that are larger than their architecture would
suggest, and uses them even to perform computations on 32-bit data.

The real issue here is that in a 32-bit environment, word-sized
pointers are 32-bits and therefore an individual process gets a 4GiB
maximum process space, which can be mapped-into a much larger space by
the kernel, and even by the underlying hardware if it's in on the deal.

> Anyway that is just too much low-level computer science for me, all
> I ever had was a seven week course on architecture and networking
> (a single week out of the seven) :)

It never hurts to learn more. Unless your brain is full. Then it
*really* hurts.

- -chris
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