Formal Verification with Yosys-SMTBMC Clifford Wolf

Bounded Liveness Properties
●
Safety properties are asserting that certain states are unreachable from a set of initial states.
– This are the properties we have been looking at so far.
●
Liveness properties are asserting that certain state inevitable are going to be reached from a set
of initial states.
– Checking liveness is hard.
– Usually this is used to prove that the circuit will always make progress, i.e. that the circuit cannot get stuck
somehow.
– In many cases bounded liveness properties are actually more useful: Assert that the target state is going to
be reached within a given timeout:
integer timeout = 0;
always @(posedge clk)
if (axis_valid && !axis_ready)
timeout