M3-SCoPE: Performance Modeling of Multi-Processor Embedded Systems for Fast Design Space Exploration - Multi-objective Design Space Exploration of Multiprocessor SoC Architectures - page 23

Some commercial tools [ 3 , 16 ] can model designs at TLM level. The schematic
entry tools simply provide a graphical interface for plugging existing database mod-
els together. These models are described and connected at the transaction-level. They
also provide shell interfaces which allow modifying the characteristics of the system
components. However, the system architecture is fixed and cannot be modified. An
alternative solution to schematic entries for system description and model generation
is using XML based descriptions. IP-XACT [ 28 ] standard describes an XML scheme
for meta-data documenting Intellectual Property (IP) used in the development, im-
plementation and verification of electronic systems. This scheme provides a standard
method to document IP that is compatible with automated integration techniques.
Several tools have been developed to support that integration [ 37 , 41 ]. The resulting
models can only configure certain parameters on the system components. However,
modifiable platforms cannot be described through IP-XACT and modeled with these
tools. Thus, the exploration of the best platform architecture cannot be performed
with these tools.
In that context, the work presented here proposes a solution to describe modifiable
architectures and automatically generate the corresponding system models. These
models can be configured by modifying the parameters of the system components
and also modifying the system architecture itself. This modeling capability will allow
the DSE tools not only to find the optimal tuning of the system components, but also
to optimize the system itself. System descriptions will be performed in a simple
XML format, although the proposed solutions can be easily adapted to other XML
descriptions.

2.2 Native Co-Simulation Infrastructure for DSE

As stated above, SystemC has been widely adopted for system modeling during last
years. SystemC provides features to describe systems from RTL descriptions up to
system-level models, in order to enable its application during all the first steps of
the design flow. Furthermore, as SystemC is a library of C++, SW designers can
integrate their C/C++ codes together with the HW platform descriptions to create
models of the entire system. Then, the SW is compiled and executed natively in the
host computer without requiring slow ISS models. As a consequence, this solution
results in very fast simulation technology.
However, this solution, which can be used to verify the system functionality,
presents several limitations in terms of additional performance estimations. The
native execution of a SW code provides no information about the temporal behavior
of the code in the target platform. Furthermore, this kind of execution of the embedded
SW does not consider any kind of processor allocation nor the effects of an operating
system. Finally, the HW/SW interfaces are not adequately modeled, so the effects of
interrupts, device drivers or bus contentions are not taken into account.
SCoPE is a library that provides the extensions required by SystemC to enable
the use of native SW execution together with SystemC HW descriptions in order to