Intel Core™ i7-860 Processor (8M Cache, 2.80 GHz) BX8060517860 User Manual

Datasheet

55

This is the Memory Controller Write Credit Thresholds register. A Write threshold is 
defined as the number of credits reserved for this priority (or higher) request. It is 
required that High threshold be greater than or equal to Crit threshold, and that both 
be lower than the total Write Credit init value. BIOS must initialize this register with 
appropriate values depending on the level of Isoch support in the platform. The new 
values take effect immediately upon being written.

Register programming rules:

• CRIT threshold value must correspond to the number of critical RTIDs reserved at 

the IOH.

• HIGH threshold value must correspond to the sum of critical and high RTIDs 

reserved at the IOH (which must not exceed 30).

• Set MC_Channel_*_WAQ_PARAMS.ISOCENTRYTHRESHHOLD equal to (31-CRIT).

This register contains part of the address of the last patrol scrub request issued. When 
running Memtest, the failing address is logged in this register on Memtest errors. 
Software can write the next address to be scrubbed into this register. Patrol scrubs 
must be disabled to reliably write this register.

12:8

RW

4

HIGH. High Credit Threshold. 

4:0

RW

3

CRIT. Critical Credit Threshold. 

29:14

RW

0

PAGE. 
This field contains the row of the last scrub issued. Can be written to specify the 

next scrub address with STARTSCRUB in the MC_SCRUB_CONTROL register.

13:0

RW

0

COLUMN. 
This field contains the column of the last scrub issued. Can be written to specify 

the next scrub address with STARTSCRUB in the MC_SCRUB_CONTROL register.