6 Configuration and Checkpointing

Simics includes a configuration system used to describe the state of the simulated machines.

Simics's configuration system is object-oriented: a simulated machine is represented as a set of objects that interact when the simulated time advances. Typically, processors, memories and devices are modeled as objects. Each object is defined by a number of properties that are called attributes. A processor object, for example, will have an attribute called freq_mhz to define its clock frequency (in MHz).

Simics's configuration system is flexible: it is possible to create and delete objects dynamically, as well as access the attributes of all objects for reading and writing at any time.

Simics's configuration system allows its elements to be saved so that a complete simulated machine state can be written to a set of files. This set of files is called a checkpoint.

This chapter describes the Simics configuration system as well as the different layers built on top of it to handle more specific tasks:

• Checkpoints: how a simulated state is saved and restored via checkpointing;
• Inspection: how the simulated state can be examined and changed during simulation;
• Start Scripts: the components and scripts used to define the initial state of a machine in the examples provided with Simics.
Note: Not all kinds of connections with real network, or with real file systems, will continue to work properly if you pause the simulation for a shorter or lengthier time. This applies to most stateful connections, for example NFS, TCP, etc.

For the same reason, not all kinds of connections with the real world can be saved in a checkpoint and successfully restored at a later time. Hence, make a habit to disconnect such services before pausing the simulation, or before saving a checkpoint.

• 6.1 Basics
• 6.2 Checkpointing
• 6.3 Inspecting the Configuration
• 6.4 Components
• 6.5 Object Name
• 6.6 Ready-to-run Configurations