Top of Upper Usable DRAM (TOUUD_0_0_0_PCI) – Offset A8 - 1.3 - ID:767626 | 12th Generation Intel® Core™ Processor Datasheet Volume 2 of 2

Introduction
Processor Configuration Register Definitions and Address Ranges
D0:F0 Host Bridge and DRAM Controller - DMIBAR Registers
D0:F0 Host Bridge and DRAM Controller - GFXVTBAR Registers
D0:F0 Host Bridge and DRAM Controller - GTTMMADR Registers (part 1)
D0:F0 Host Bridge and DRAM Controller - GTTMMADR Registers (part 2)
D0:F0 Host Bridge and DRAM Controller - Host Bridge/DRAM Registers (part 1)
- Revision ID (RID_0_0_0_PCI)
D0:F0 Host Bridge and DRAM Controller - Host Bridge/DRAM Registers (part 2)
D0:F0 Host Bridge and DRAM Controller - MCHBAR Host Controller Registers (part 1)
- GFX VT Range Base Address Register (GFXVTBAR_0_0_0_MCHBAR_NCU)
- VT DMI PEG VC0 Range Base Address Register (VTDPVC0BAR_0_0_0_MCHBAR_NCU)
D0:F0 Host Bridge and DRAM Controller - MCHBAR Host Controller Registers (part 2)
D0:F0 Host Bridge and DRAM Controller - MCHBAR Memory Controller Registers (part 2)
D0:F0 Host Bridge and DRAM Controller - MCHBAR Memory Controller Registers (part 3)
D0:F0 Host Bridge and DRAM Controller - MCHBAR Memory Controller Registers (part 4)
D0:F0 Host Bridge and DRAM Controller - MCHBAR Memory Controller Registers (part 5)
D0:F0 Host Bridge and DRAM Controller - MCHBAR Power Management Registers (part 1)
D0:F0 Host Bridge and DRAM Controller - MCHBAR Power Management Registers (part 2)
D0:F0 Host Bridge and DRAM Controller - PXPEPBAR PCI Express Egress Port Registers
D0:F0 Host Bridge and DRAM Controller - VTDPVC0BAR Registers
D1:F0-1 PCI Express* Controller Registers
D10:F0 Platform Monitoring Technology (PMT) Registers
D14:F0 Volume Management Device
D14:F0 Volume Management Device MEMBAR2 Registers
D2:F0 Processor Graphics
D4:F0 Dynamic Tuning Technology Registers
D6:F0 PCI Express* Controller Registers
D8:F0 Gauss Newton Algorithm Registers

Top of Upper Usable DRAM (TOUUD_0_0_0_PCI) – Offset A8

This 64 bit register defines the Top of Upper Usable DRAM.
Configuration software must set this value to TOM minus all ME stolen memory if reclaim is disabled. If reclaim is enabled, this value must be set to reclaim limit + 1byte, 1MB aligned, since reclaim limit is 1MB aligned. Address bits 19:0 are assumed to be 000_0000h for the purposes of address comparison. The Host interface positively decodes an address towards DRAM if the incoming address is less than the value programmed in this register and greater than or equal to 4GB.
BIOS Restriction: Minimum value for TOUUD is 4GB.
These bits are Intel TXT lockable.

Bit Range	Default	Access	Field Name and Description
63:42	0h	RO	Reserved
41:20	0x0	RW/L	(TOUUD) This register contains bits 41 to 20 of an address one byte above the maximum DRAM memory above 4G that is usable by the operating system. Configuration software must set this value to TOM minus all ME stolen memory if reclaim is disabled. If reclaim is enabled, this value must be set to reclaim limit 1MB aligned since reclaim limit + 1byte is 1MB aligned. Address bits 19:0 are assumed to be 000_0000h for the purposes of address comparison. The Host interface positively decodes an address towards DRAM if the incoming address is less than the value programmed in this register and greater than 4GB. All the bits in this register are locked in Intel TXT mode.
19:1	0h	RO	Reserved
0	0x0	RW/L	(LOCK) This bit will lock all writable settings in this register, including itself.

Base Data of Stolen Memory (BDSM_0_0_0_PCI)

Top of Memory (TOM_0_0_0_PCI) Base Data of Stolen Memory (BDSM_0_0_0_PCI)