Ccmd_Reg-Context Command Register - Intel 2ND GENERATION CORE PROCESSOR FAMILY DESKTOP - DATASHEET VOLUME 2 01-2011 Datasheet

Processor Configuration Registers
2.21.7 CCMD_REG—Context Command Register
This register manages context cache. The act of writing the upper most byte of the
CCMD_REG with the ICC field set causes the hardware to perform the context-cache
invalidation.
B/D/F/Type:
Address Offset:
Reset Value:
Access:
Size:
BIOS Optimal Default
Bit
63
62:61
Datasheet, Volume 2
0/0/0/VC0PREMAP
28–2Fh
0000000000000000h
RW-V, RW, RO-V
64 bits
000000000h
Reset RST/
Attr
Value PWR
RW-V 0h Uncore
RW 0h Uncore
Description
Invalidate Context-Cache (ICC)
Software requests invalidation of context-cache by setting this
field. Software must also set the requested invalidation granularity
by programming the CIRG field. Software must read back and
check the ICC field is Clear to confirm the invalidation is complete.
Software must not update this register when this field is set.
Hardware clears the ICC field to indicate the invalidation request is
complete. Hardware also indicates the granularity at which the
invalidation operation was performed through the CAIG field.
Software must submit a context-cache invalidation request through
this field only when there are no invalidation requests pending at
this remapping hardware unit.
Since information from the context-cache may be used by
hardware to tag IOTLB entries, software must perform domain-
selective (or global) invalidation of IOTLB after the context cache
invalidation has completed.
Hardware implementations reporting write-buffer flushing
requirement (RWBF=1 in Capability register) must implicitly
perform a write buffer flush before invalidating the context cache.
Context Invalidation Request Granularity (CIRG)
Software provides the requested invalidation granularity through
this field when setting the ICC field:
00 = Reserved.
01 = Global Invalidation request.
10 = Domain-selective invalidation request. The target domain-id
must be specified in the DID field.
11 = Device-selective invalidation request. The target source-
id(s) must be specified through the SID and FM fields, and
the domain-id (that was programmed in the context-entry
for these device(s)) must be provided in the DID field.
Hardware implementations may process an invalidation request by
performing invalidation at a coarser granularity than requested.
Hardware indicates completion of the invalidation request by
clearing the ICC field. At this time, hardware also indicates the
granularity at which the actual invalidation was performed through
the CAIG field.
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