Intel E3-1275 Datasheet download pdf (Page 28)

Processor Configuration Registers

28 Datasheet, Volume 2

2.3.4.3 Memory Remapping

An incoming address (referred to as a logical address) is checked to see if it falls in the

memory re-map window. The bottom of the re-map window is defined by the value in

the REMAPBASE register. The top of the re-map window is defined by the value in the

REMAPLIMIT register. An address that falls within this window is remapped to the

physical memory starting at the address defined by the TOLUD register. The TOLUD

2.3.4.4 Hardware Remap Algorithm

The following pseudo-code defines the algorithm used to calculate the DRAM address to

be used for a logical address above the top of physical memory made available using

re-claiming.

IF (ADDRESS_IN[38:20] REMAP_BASE[35:20]) AND

(ADDRESS_IN[38:20] REMAP_LIMIT[35:20]) THEN

ADDRESS_OUT[38:20] = (ADDRESS_IN[38:20] – REMAP_BASE[35:20]) +

0000000b and TOLUD[31:20]

ADDRESS_OUT[19:0] = ADDRESS_IN[19:0]

2.3.4.5 Programming Model

The memory boundaries of interest are:

• Bottom of Logical Address Remap Window defined by the REMAPBASE register,

which is calculated and loaded by BIOS.

• Top of Logical Address Remap Window defined by the REMAPLIMIT register, which

is calculated and loaded by BIOS.

• Bottom of Physical Remap Memory defined by the existing TOLUD register.

• Top of Physical Remap Memory, which is implicitly defined by either 4 GB or TOM

minus Manageability Engine stolen size.

Mapping steps:

1. Determine TOM

2. Determine TOM minus ME stolen size

3. Determine MMIO allocation

4. Determine TOLUD

5. Determine GFX stolen base

6. Determine GFX GTT stolen base

7. Determine TSEG base

8. Determine remap base/limit

9. Determine TOUUD

Figure 2-5 and Figure 2-6 show the two possible general cases of remapping.

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Intel E3-1275 Datasheet Page 28