Processor Configuration Registers
Example: 5 GB of Physical Memory, with 1 GB allocated to Memory Mapped IO
• Populated Physical Memory = 5 GB
• Address Space allocated to memory mapped IO (including Flash, APIC, and Intel
TXT) = 1 GB
• Remapped Physical Memory = 1 GB
• TOM – 01_4000_0000h (5 GB)
• ME stolen size – 00000b (0 MB)
• TOUUD – 01_8000_0000h (6 GB) (1 MB aligned)
• TOLUD – 00_C000_000h (3 GB)
• REMAPBASE – 01_4000_0000h (5 GB)
• REMAPLIMIT – 01_7FF0_0000h (6 GB–1)
The Remap window is inclusive of the Base and Limit addresses. In the decoder
A[19:0] of the Remap Base Address are assumed to be 0s. Similarly, A[19:0] of the
Remap Limit Address are assumed to be Fs. Thus, the bottom of the defined memory
range will be aligned to a MB boundary and the top of the defined range will be one less
than a MB boundary.
Setting the Remap Base register to a value greater than that programmed into the
Remap Limit register disables the remap function.
Software Responsibility and Restrictions
• BIOS is responsible for programming the REMAPBASE and REMAPLIMIT registers
based on the values in the TOLUD, TOM, and Intel ME stolen size registers.
• The amount of remapped memory defined by the REMAPBASE and REMAPLIMIT
registers must be equal to the amount of physical memory between the TOLUD
and the lower of either 4 GB or TOM minus the Intel ME stolen size.
• Addresses of MMIO region must not overlap with any part of the Logical Address
Memory Remap range.
• When TOM is equal to TOLUD, remap is not needed and must be disabled by
programming REMAPBASE to a value greater than the value in the REMAPLIMIT
register.
Interaction with other Overlapping Address Space
The following Memory Mapped IO address spaces are all logically addressed below 4 GB
where they do not overlap the logical address of the re-mapped memory region:
GFXGTTstolen
GFXstolen
At (TOLUD – GFXstolensize) to TOLUD
At ((TOLUD – GFXstolensize) – GFXGTTstolensize) to (TOLUD –
GFXstolensize)
TSEG
At ((TOLUD – GFXstolensize – GFXGTTstolensize) – TSEGSIZE) to
(TOLUD – GFXGTTstolensize – GFXstolensize)
High BIOS
Reset vector just under 4 GB boundary (Positive decode to DMI
occurs)
XAPIC
At fixed address below 4 GB
At fixed address below 4 GB
Local APIC
Datasheet, Volume 2
33
INTEL [ INTEL ]
