Specifications

Intel
®
Quark SoC X1000 Core
October 2013 Developer’s Manual
Order Number: 329679-001US 127
System Management Mode (SMM) Architectures—Intel
®
Quark Core
8.0 System Management Mode (SMM) Architectures
8.1 SMM Overview
The Intel
®
Quark SoC X1000 Core supports four modes: Real, Virtual-86, Protected,
and System Management Mode (SMM). As an operating mode, SMM has a distinct
processor environment, interface and hardware/software features.
SMM provides system designers with a means of adding new software-controlled
features to computer products that operate transparently to the operating system and
software applications. SMM is intended for use only by system firmware, not by
applications software or general purpose systems software.
The SMM architectural extension consists of the following elements:
1. System Management Interrupt (SMI#) hardware interface.
2. Dedicated and secure memory space (SMRAM) for SMI# handler code and
processor state (context) data with a status signal (SMIACT#) for to decoding
access to that memory space. (The SMBASE address is relocatable and can also be
relocated to non-cacheable address space.)
3. Resume (RSM) instruction, for exiting the System Management Mode.
4. Special Features such as I/O-Restart, for transparent power management of I/O
peripherals, and Auto HALT Restart.
8.2 Terminology
The following terms are used throughout the discussion of System Management Mode.
SMM System Management Mode. This is the operating environment
that the processor (system) enters when the System
Management Interrupt is being serviced.
SMI# System Management Interrupt. This is part of the SMM
interface. When SMI# is asserted (low) it causes the processor
to invoke SMM. The SMI# pin is the only means of entering
SMM.
SMM Handler System Management Mode handler. This is the code that is
executed when the processor is in SMM. An example application
that this code might implement is a power management control
or a system control function.
RSM Resume instruction. This instruction is used by the SMM handler
to exit SMM and return to the operating system or application
process that was interrupted.
SMRAM Physical memory dedicated to SMM. The SMM handler code and
related data reside in this memory. This memory is also used by
the processor to store its context before executing the SMM
handler. The operating system and applications do not have
access to this memory space.