Storage Control Registers (Non-Architected); Memory Management Unit Control Register 0 (Mmucr0) - IBM A2 User Manual

6.18 Storage Control Registers (Non-Architected)

This section describes the implementation-specific (nonarchitected) storage control registers.

6.18.1 Memory Management Unit Control Register 0 (MMUCR0)

The MMUCR0 register is written from a GPR using mtspr and can be read into a GPR using mfspr. In addi-
tion, the MMUCR0[TGS], [TS] and [TID] fields are updated with the TGS, TS, and TID fields of the selected
ERAT entry when an eratre instruction is executed. Conversely, the TGS, TS, and TID fields of the selected
ERAT entry are updated with the value of the MMUCR0[TGS], [TS], and [TID] fields when an eratwe instruc-
tion is executed. Other functions associated with fields of the MMUCR0 are described in more detail in the
sections that follow.
Register Short Name:
Decimal SPR Number:
Initial Value:
Slow SPR:
Guest Supervisor Mapping:
Bits Field Name
32 ECL
33 TID_NZ
34 TGS
35 TS
36:37 TLBSEL
38:49 ///
50:63 TID
Extended Class (ECL) Field
The ECL field is used to designate the value to transfer for the ExtClass field of the ERAT entries for eratre
and eratwe instructions. The ECL field serves as an auxiliary extension to the class identifier field in the
ERAT entries, but is decoupled from the RS source register class field used in the ERAT management
instructions. The eratilx and tlbilx and the erativax and tlbivax instructions assume an ExtClass value of
Version 1.3
October 23, 2012
MMUCR0
1020
0x0000000000000000
Y
Initial
Value
0b0 Extended Class
Used to transfer the ExtClass field of the selected ERAT entry.
0b0 Translation ID Non-Zero
Used to transfer the TID_NZ field of the selected ERAT entry.
0b0 Translation Guest State
Used to transfer the TGS bit of the selected ERAT entry.
0b0 Translation Space
Used to transfer the TS bit of the selected ERAT entry.
0b00 TLB Select
ERAT structure selection:
00 Reserved.
01 Reserved.
10 I-ERAT.
11 D-ERAT.
0x0 Reserved
0x0 Translation ID
Used to transfer the TID field of the selected ERAT entry.
Read Access:
Write Access:
Duplicated for Multithread:
Notes:
Scan Ring:
Description
User's Manual
A2 Processor
Hypv
Hypv
Y
AM
func
Memory Management
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