Fix msg_iov accounting.

Fixes msg_iov advance.

Signed-off-by: Matt Benjamin <matt@linuxbox.com>
Add MDataPing.

Adds a new MDataPing message type, used for streamlined data
payload testing.

Signed-off-by: Matt Benjamin <matt@linuxbox.com>
Do a hexdump on it.

Signed-off-by: Matt Benjamin <matt@linuxbox.com>
Move buffer placement logic into xio_place_buffers.

Signed-off-by: Matt Benjamin <matt@linuxbox.com>
Fix ref-to-ptr params.

Signed-off-by: Matt Benjamin <matt@linuxbox.com>
Enable registration for -all- buffers.

Signed-off-by: Matt Benjamin <matt@linuxbox.com>