System Management Mode Programming Model; Entering System Management Mode - Intel Quark SoC X1000 Core Developer's Manual

Auto HALT Restart. It is possible for the SMI# request to interrupt the HALT state.
The SMI# handler can tell the RSM instruction to return control to the HALT instruction
or to return control to the instruction following the HALT instruction by appropriately
setting the Auto HALT Restart slot. The default operation is to restart the HALT
instruction.
I/O Trap Restart. If the SMI# interrupt was generated on an I/O access to a
powered-down device, the SMI# handler can tell the RSM instruction to re-execute that
I/O instruction by setting the I/O Trap Restart slot.
SMBASE Relocation. The system can relocate the SMRAM by setting the SMBASE
Relocation slot in the state save area. The RSM instruction sets the SMBASE in the
processor based on the value in the SMBASE Relocation slot. The SMBASE must be 32-
Kbyte aligned.
For further details on these SMM features, see
If the processor detects invalid state information, it enters the shutdown state. This
happens only in the following situations:
• The value stored in the SMBASE slot is not a 32-Kbyte aligned address.
• A reserved bit of CR4 is set to 1.
• A combination of bits in CR0 is illegal; namely, (PG=1 and PE=0) or (NW=1 and
CD=0).
In shutdown mode, the processor stops executing instructions until an NMI interrupt is
received or reset initialization is invoked. The processor generates a special bus cycle to
indicate it has entered shutdown mode.
Note: INTR and SMI# also brings the processor out of a shutdown that is encountered due to
invalid state information from SMM execution. Make sure that INTR and SMI# are not
asserted if SMM routines are written such that a shutdown occurs.
8.4

System Management Mode Programming Model

8.4.1

Entering System Management Mode

SMM is one of the major operating modes, on a level with Protected Mode, Real Mode
or Virtual-86 Mode.
three modes and then return.
®
Intel Quark SoC X1000 Core
Developer's Manual
134
®
Intel Quark Core—System Management Mode (SMM) Architectures
Figure 58 shows how the processor can enter SMM from any of the
Section 8.5.
Order Number: 329679-001US
October 2013