hi all, I have write a simple example in the server side: struct node{ l4_threadid_t sender; unsigned short flags; struct node* next; }THREADNODE, *PTHREADNODE; typedef struct node{ char buffer[4096]; PTHREADNODE head; }FF, *PFF; int sender_is_in_queue(PFF ff, l4_threadid_t sender) { PTHREADNODE p; p = ff->head; while(p != NULL && !thread_equal(p->sender, sender)) { p = p->next; } if (p == NULL) return -1; else return 0; } ...... there not error when I compile the server source file, but when I run them: __handle_pf(): L4RM: page fault: no entry in region list I use objdump command to find the error and find it was in the place: p = ff->head; could someone give me some advice? thank you and bestwishes! -- fang,