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
