Il 21/11/2013 10:11, Lei Li ha scritto: > +static int qemu_local_ram_load(QEMUFile *f, void *opaque, > + uint64_t flags) > +{ > + QEMUFileLocal *s = opaque; > + ram_addr_t addr; > + struct iovec iov; > + ssize_t ret = -EINVAL; > + > + /* > + * PIPE file descriptor will be received by another callback > + * get_buffer. > + */ > + if (pipefd_passed) { > + void *host; > + /* > + * Extract the page address from the 8-byte record and > + * read the page data from the pipe. > + */ > + addr = qemu_get_be64(s->file); > + host = qemu_get_ram_ptr(addr); > + > + iov.iov_base = host; > + iov.iov_len = TARGET_PAGE_SIZE; > + > + /* The flag SPLICE_F_MOVE is introduced in kernel for the page > + * flipping feature in QEMU, which will movie pages rather than > + * copying, previously unused. > + * > + * If a move is not possible the kernel will transparently falls > + * back to copying data. > + * > + * For older kernels the SPLICE_F_MOVE would be ignored and a copy > + * would occur. > + */ > + ret = vmsplice(s->pipefd[0], &iov, 1, SPLICE_F_MOVE); > + if (ret == -1) { > + if (errno != EAGAIN && errno != EINTR) { > + fprintf(stderr, "vmsplice() load error: %s", > strerror(errno)); > + return ret; > + } > + DPRINTF("vmsplice load error\n"); > + } else if (ret == 0) { > + DPRINTF(stderr, "load_page: zero read\n"); > + } > + > + DPRINTF("vmsplice (read): %zu\n", ret); > + return ret; > + } > + > + return 0; > +}
I think you need to return -EINVAL if there is no pipe. Paolo