Hi all, After implementing the ToyVM::runApplication method, I run the ToyVM binary, A segmentation fault occurs on starting ToyThread. My code is: void ToyVM::runApplication(int argc, char** argv) { ToyThread *tt = new ToyThread(this); mainThread = tt; typedef void (*vmkitThreadfptr)(vmkit::Thread*); void (*mainStartPtr)(vmkit::Thread*); mainStartPtr = (vmkitThreadfptr)(&mainStart); startRes = tt->start(mainStartPtr); } by tracing, the error occurs in the following line of LockNormal::lock() method pthread_mutex_lock((pthread_mutex_t*)&internalLock); Best regards, Mkh