Specifications

212 AMD Geode™ GeodeROM Functional Specification
System Management Mode Software
32087C
15.1 Architecture
The SMI handler is designed so no changes to the existing firmware are required. Individual binary components, called Vir-
tual Support Modules (VSM), provide specific pieces of functionality. Each VSM is isolated from every other VSM in terms
of functionality and code. VSA2 technology is architected using a client-server model. The VSM dispatcher is called the
System Manager and acts as the server. The System Manager code executes as soon as an SMI occurs. It saves the state
of the system and prepares the VSA2 technology system to run. Figure 15-1 "VSM Client-Server Model Example" on page
212 shows an example of the VSM client-server methodology.
Each of the remaining VSMs (clients) is an endless message-processing loop. For example, in the course of processing an
“initialization” message, a VSM may register to be notified upon the occurrence of various types of events (traps, timers,
etc.). After processing the initialization message, the VSM retrieves the next message out of its queue via a system-call
macro. The macro allows control to return to the System Manager, that is then free to call any VSM, or cause the system to
exit the SMI handler.
VSA2 technology is Geode hardware-specific. The System Manager contains the hardware-dependent implementation.
Two mechanisms for communication exist with and within VSA2 technology, and are implemented within the System Man-
ager VSM.
1) VR (virtual registers) (see Section 15.9 “Virtual Registers” on page 219) are used for interprocess or module communi-
cation between VSMs. They are also the means of communication between external application or driver software and
VSA2 software.
2) VSA2 software messages are used to communicate with other VSMs and the System Manager.
Figure 15-1. VSM Client-Server Model Example
System
PM
VSM
Audio
VSM
Graphics
VSM
VSM Architecture
Manager VSM
(Server)
(Client)
(Client)
(Client)
(SMI Handler)
Power Management
Subsystem
XpressAUDIO™
Subsystem
XpressGRAPHICS™
Subsystem
System
Call
System
Call
System
Call
Event (SMI)
Event (SMI)
Event (SMI)