
2-73
2
PRELIMINARY
System Management Mode
System Management Mode
2-73
Table 2-36. SMM Memory Space Header
NAME
DESCRIPTION
SIZE
DR7
The contents of Debug Register 7.
4 Bytes
EFLAGS
The contents of Extended Flags Register.
4 Bytes
CR0
The contents of Control Register 0.
4 Bytes
Current IP
The address of the instruction executed prior to servicing SMI interrupt.
4 Bytes
Next IP
The address of the next instruction that will be executed after exiting SMM mode.
4 Bytes
CS Selector
Code segment register selector for the current code segment.
2 Bytes
CS Descriptor
Code segment register descriptor for the current code segment.
8 Bytes
CPL
Current privilege level for current code segment.
2 Bits
N
Nested SMI Indicator
If N = 1: current SMM is being serviced from within SMM mode.
If N = 0: current SMM is not being serviced from within SMM mode.
1 Bit
IS
Internal SMI Indicator
If IS =1: current SMM is the result of an internal SMI event.
If IS =0: current SMM is the result of an external SMI event.
1 Bit
H
SMI during CPU HALT state indicator
If H = 1: the processor was in a halt or shutdown prior to servicing the SMM
interrupt.
1 Bit
S
Software SMM Entry Indicator.
If S = 1: current SMM is the result of an SMINT instruction.
If S = 0: current SMM is not the result of an SMINT instruction.
1 Bit
P
REP INSx/OUTSx Indicator
If P = 1: current instruction has a REP prefix.
If P = 0: current instruction does not have a REP prefix.
1 Bit
I
IN, INSx, OUT, or OUTSx Indicator
If I = 1: if current instruction performed is an I/O WRITE.
If I = 0: if current instruction performed is an I/O READ.
1 Bit
C
Code Segment writable Indicator
If C = 1: the current code segment is writable.
If C = 0: the current code segment is not writable.
1 Bit
I/O
Indicates size of data for the trapped I/O write:
01h = byte
03h = word
0Fh = dword
2 Bytes
I/O Write Address
Processor port used for the trapped I/O write.
2 Bytes
I/O Write Data
Data associated with the trapped I/O write.
4 Bytes
ESI or EDI
Restored ESI or EDI value. Used when it is necessary to repeat a REP OUTSx or
REP INSx instruction when one of the I/O cycles caused an SMI# trap.
4 Bytes
Note: INSx = INS, INSB, INSW or INSD instruction.
Note: OUTSx = OUTS, OUTSB, OUTSW and OUTSD instruction.