MSG Update

/* An update_iovec describes a single template update */
struct onload_template_msg_update_iovec {
  void*    otmu_base;         /* Pointer to new data */
  size_t   otmu_len;          /* Length of new data */
  off_t    otmu_offset;       /* Offset within template to update */
  unsigned otmu_flags;        /* For future use.  Must be set to 0. */
};