Intel i7-3920XM Extreme AW8063801009607 User Manual

Datasheet, Volume 2

263

Processor Configuration Registers 

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Fault-recording Register offset (FRO) 
This field specifies the location to the first fault recording register 

relative to the register base address of this remapping hardware 

unit.
If the register base address is X, and the value reported in this 

field is Y, the address for the first fault recording register is 

calculated as X+(16*Y).

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1b

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Isochrony (ISOCH) 
0 = Remapping hardware unit has no critical isochronous 

requesters in its scope.

1 = Remapping hardware unit has one or more critical 

isochronous requesters in its scope. To ensure isochronous 

performance, software must ensure invalidation operations 

do not impact active DMA streams from such requesters. 

This implies, when DMA is active, software performs page-

selective invalidations (and not coarser invalidations). 

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Zero Length Read (ZLR) 
0 = Remapping hardware unit blocks (and treats as fault) zero 

length DMA read requests to write-only pages.

1 = Remapping hardware unit supports zero length DMA read 

requests to write-only pages.

DMA remapping hardware implementations are recommended to 

report ZLR field as set.

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100110b

Uncore

Maximum Guest Address Width (MGAW) 
This field indicates the maximum DMA virtual addressability 

supported by remapping hardware. The Maximum Guest Address 

Width (MGAW) is computed as (N+1), where N is the value 

reported in this field. For example, a hardware implementation 

supporting 48-bit MGAW reports a value of 47h (101111b) in this 

field.
If the value in this field is X, untranslated and translated DMA 

requests to addresses above 2^(x+1)–1 are always blocked by 

hardware. Translations requests to address above 2^(x+1)–1 

from allowed devices return a null Translation Completion Data 

Entry with R=W=0.
Guest addressability for a given DMA request is limited to the 

minimum of the value reported through this field and the 

adjusted guest address width of the corresponding page-table 

structure. (Adjusted guest address widths supported by 

hardware are reported through the SAGAW field).
Implementations are recommended to support MGAW at least 

equal to the physical addressability (host address width) of the 

platform.

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0h