Publishing System Memory; Memory Interleaving - Intel BB5520UR Technical Product Specification

Functional Architecture
3.3.4

Publishing System Memory

The BIOS displays the "Total Memory" of the system during POST if the "Quiet
Boot" is disabled in the BIOS Setup. This is the total size of memory discovered by
the BIOS during POST, and is the sum of the individual sizes of installed DDR3
DIMMs in the system.
The BIOS also provides the total memory of the system in the BIOS setup (Main
page and Advanced | Memory Configuration Page). This total is the same as the
amount described by the previous bullet.
The BIOS displays the "Effective Memory" of the system in the BIOS Setup
(Advanced | Memory Configuration Page). The term Effective Memory refers to the
total size of all active DDR3 DIMMs (not disabled) and not being used as redundant
units in Mirrored Channel Mode.
If Quiet Boot is disabled, the BIOS displays the total system memory on the
diagnostic screen at the end of POST. This total is the same as the amount
described by the first bullet.
3.3.4.1 Memory Reservation for Memory-mapped Functions
A region of size of 40 MB of memory below 4 GB is always reserved for mapping chipset,
processor, and BIOS (flash) spaces as memory-mapped I/O regions. This region appears as a
loss of memory to the operating system.
This (and other) reserved regions are reclaimed by the operating system if PAE is enabled in
the operating system.
In addition to this memory reservation, the BIOS creates another reserved region for memory-
mapped PCI Express* functions, including a standard 64 MB or 256 MB of standard PCI
Express* MMIO configuration space. This is based on the setup selection, "Maximize Memory
below 4GB".
If this is set to "Enabled", the BIOS maximizes usage of memory below 4 GB, for an operating
system without PAE capability, by limiting PCI Express* Extended Configuration Space to 64
buses, rather than the standard 256 buses.
3.3.4.2 High-Memory Reclaim
When 4 GB or more of physical memory is installed (physical memory is the memory installed
as DDR3 DIMMs), the reserved memory is lost. However, the Intel
a feature called high-memory reclaim, which allows the BIOS and the operating system to
remap the lost physical memory into system memory above 4 GB (the system memory is the
memory the processor can see).
The BIOS always enables high-memory reclaim if it discovers installed physical memory equal
to or greater than 4 GB. For the operating system, you can recover the reclaimed memory only
if the PAE feature in the processor is supported and enabled. Most operating systems support
this feature. For details, see your operating system's relevant manuals.
3.3.5

Memory Interleaving

® ®
The Intel Xeon Processor 5500 Series supports the following memory interleaving mode:
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Intel® Server Boards S5520HC, S5500HCV, and S5520HCT TPS
Intel order number E39529-013
®
5500/5520 I/O Hub provides
Revision 1.8