Hi All Is it the correct step to invoke a single step? It will fail when currec IP hit a breakpoint, but i can't find any different than the gdb stub. static int sstep_flags = SSTEP_ENABLE | SSTEP_NOIRQ | SSTEP_NOTIMER;CPUArchState *cpu = first_cpu;cpu_single_step(cpu, sstep_flags);vm_start(); Thanksfrom Peter