There are two main options available for coremark SIM, ITERATIONS
Controls how many iteartions are run. By default this value is 0 and will cause coremark to run >10s. For simulation and verilator, set to 1 for a reduced run
make distclean; make SIM=1 ITERATIONS=1 SIM=1 matces the verilator UART baudrates
make distclean; make ITERATIONS=1/N