Adding an option to gem5

Say we want to add option “xyz” to our simulator

1) Add it to configs/common/Options.py: In addCommonOptions() function add parser.add_option(“–xyz”, action=“store_true”)

2) Add this option as a parameter in base cpu class. In src/cpu/BaseCPU.py add this to the class BaseCPU:

xyz = Param.Bool(False, “Enable line trace”)

3) Add xyz as a public class member in base class of cpu in src/cpu/base.hh

bool xyz;

4) Add support for xyz in constructor of base class for cpu in src/cpu/base.cc

xyz = params()->xyz;

5) Pass the option from the config script to the cpu class. After instantiating cpus i.e.

system = System(cpu = [CPUClass(cpu_id=i, num_cores=np) for i in xrange(np)] …. )

etc, do

system.cpu[0].xyz = options.xyz

6) Now you can use the true/false boolean xyz to do conditional operation in you cpu member functions as:

if ( xyz ) { …. } else { … }

We have now added a new option to gem5.