GXLV Datasheet, PDF (52/247 Pages) National Semiconductor (TI) – Geode™ GXLV Processor Series Low Power Integrated x86 Solutions

Processor Programming (Continued)
Table 3-11. Configuration Registers
Bit
Name
Description
Index C1h
CCR1 — Configuration Control Register 1 (R/W)
Default Value = 00h
7:3
RSVD
Reserved: Set to 0.
2:1
SMAC
System Management Memory Access:
If = 00: SMM is disabled.
If = 01: SMI# pin is active to enter SMM. SMINT instruction is inactive.
If = 10: SMM is disabled.
If = 11: SMINT instruction is active to enter SMM. SMI# pin is inactive.
Note: SMI_LOCK (CCR3[0]) must = 0, or the CPU must be in SMI mode, to write this bit.
0
RSVD
Reserved: Set to 0.
Note: Bits 1 and 2 are cleared to zero at reset.
Index C2h
CCR2 — Configuration Control Register 2 (R/W)
Default Value = 00h
7
USE_SUSP Enable Suspend Pins:
If = 1: SUSP# input and SUSPA# output are enabled.
If = 0: SUSP# input is ignored.
6
RSVD
Reserved: This is a test bit that must be set to 0.
5
RSVD
Reserved: Set to 0.
4
WT1
Write-Through Region 1:
If = 1: Forces all writes to the address region between 640 KB to 1 MB that hit in the on-chip cache to
be issued on the external bus.
3
SUSP_HLT Suspend on HALT:
If = 1: CPU enters Suspend mode following execution of a HALT instruction.
2
LOCK_NW
Lock NW Bit:
If = 1: Prohibits changing the state of the NW bit (CR0[29]) (refer to Table 3-7 on page 49).
Set to 1 after setting NW.
1:0
RSVD
Reserved: Set to 0.
Note: All bits are cleared to zero at reset.
Index C3h
CCR3 — Configuration Control Register 3 (R/W)
Default Value = 00h
7
LSS_34
Load/Store Serialize 3 GB to 4 GB:
If = 1: Strong R/W ordering imposed in address range C0000000h to FFFFFFFFh:
6
LSS_23
Load/Store Serialize 2 GB to 3 GB:
If = 1: Strong R/W ordering imposed in address range 80000000h to BFFFFFFFh:
5
LSS_12
Load/Store Serialize 1 GB to 2 GB:
If = 1: Strong R/W ordering imposed in address range 40000000h to 7FFFFFFFh
4
MAPEN
Map Enable:
If = 1: All configuration registers are accessible. All accesses to I/O Port 22h are trapped.
If = 0: Only configuration registers Index C1h-C3h, CDh-CFh FEh, FFh (CCRn, SMAR, DIRn) are
accessible. Other configuration registers (including PCR, SMHRn, GCR, VGACTL, VGAM0) are not
accessible.
3
SUSP_SMM_EN Enable Suspend in SMM Mode:
If 0 = SUSP# ignored in SMM mode.
If 1 = SUSP# recognized in SMM mode.
2
RSVD
Reserved: Set to 0.
1
NMI_EN
NMI Enable:
If = 1: NMI is enabled during SMM.
If = 0: NMI is not recognized during SMM.
Note: SMI_LOCK (CCR3[0]) must = 0 or the CPU must be in SMI mode to write to this bit.
0
SMI_LOCK SMM Register Lock:
If = 1: SMM Address Region Register (SMAR[31:0]), SMAC (CCR1[2]), USE_SMI (CCR1[1])
cannot be modified unless in SMM routine. Once set, SMI_LOCK can only be cleared by asserting
the RESET pin.
Note: All bits are cleared to zero at reset.
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