Memory Remapping

Memory Remapping

Hi all.

One technical question.

I know how PAE, 64bit addressing, Segmentation and protection on 386 or PentiumPro work

I don't know what happens when I enable the memory remapping option on the BIOS.

Where are the addresses of the memory mapping devices moved to?

1. Close to 64GB because my Processor has got only 36bit of ABUS, regardless of motherboard and chipset (I have a E6600 now)

2. Close to 8GB because my Motherboard has only a maximum addressable of 8GB, so it is really likely that it has only 33 lines of ABUS, so regardless of processor and chipset

3. In any case close tothe incredible address 2^64, because the complete address space of the processor is 64bit, so regardless of the 36bit of ABUS, motherboard issues or whatever else. (I have written this one just not to finish with only 2 options, but I wouldn't bet on it a single euro).

The same question is: If I have Windows64bit, 8GB on my motherboard which supports 8GB, and I have enabled the Memory Remapping, would I be able to address all the 8GB or again I can have the limit to 6.8GB - 7.5GB?

If it is 8GB because the addresses are moved closed to 64GB, why the hell my motherboard is limited to only 8GB, if all the things tell me that I am able to address up to 64GB?

Thank you for your help.

ZeePrime, ITA.

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Our engineering contacts responded:

You asked about what memory remapping in the BIOS settings does. The BIOS vendor is probably the right venue if you need to know how a given BIOS vendor implements that product.

If you are asking in what physical address range your 8GB DIMMs are located, thats a mainboard vendor question. The motherboard design may choose to implement 33 physical address pins to save cost; regardless, the CPU provides 36 address pins (for E6600).

If you are asking why the OS reports seeing less than 8GB, that may be from a number of things. For example, SMM firmware that the PC manufacturer provides needs its own memory; that chunk of memory is carved out for SMM use, only without the OS knowing about it. There may be certain devices in the system that need to reserve a certain physical memory range for communication. The BIOS hands out whats left over of the physical memory and gives that to the OS to do its work.

If you want to know the initialization behavior of certain peripherals or video cards at boot time, the device vendor is the right place to ask for information.

End-user applications only run in the virtual address space, not in physical address space. The connection between different address spaces that you are trying to draw doesnt make much sense.


Lexi S.

IntelSoftware NetworkSupport

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