+#ifdef PT_IO
+ /* OpenBSD 3.1, NetBSD 1.6 and FreeBSD 5.0 have a new PT_IO request
+ that promises to be much more efficient in reading and writing
+ data in the traced process's address space. */
+
+ {
+ struct ptrace_io_desc piod;
+
+ /* NOTE: We assume that there are no distinct address spaces for
+ instruction and data. */
+ piod.piod_op = write ? PIOD_WRITE_D : PIOD_READ_D;
+ piod.piod_offs = (void *) memaddr;
+ piod.piod_addr = myaddr;
+ piod.piod_len = len;
+
+ if (ptrace (PT_IO, PIDGET (inferior_ptid), (caddr_t) &piod, 0) == -1)
+ {
+ /* If the PT_IO request is somehow not supported, fallback on
+ using PT_WRITE_D/PT_READ_D. Otherwise we will return zero
+ to indicate failure. */
+ if (errno != EINVAL)
+ return 0;
+ }
+ else
+ {
+ /* Return the actual number of bytes read or written. */
+ return piod.piod_len;
+ }
+ }
+#endif
+