On Thu, Jun 24, 2021 at 11:10:41AM +0800, Chen Huang wrote: > In userspace, I perform such operation: > > fd = open("/tmp/test", O_RDWR | O_SYNC); > access_address = (char *)mmap(NULL, uio_size, PROT_READ, MAP_SHARED, uio_fd, 0); > ret = write(fd, access_address + 2, sizeof(long)); ... you know that accessing this at unaligned offsets isn't going to work. It's completely meaningless. Why are you trying to do it?