OS-3752 Increase IOV_MAX to at least 1024

*** 19,28 ****
--- 19,29 ----
   * CDDL HEADER END
   */
  
  /*
   * Copyright (c) 1982, 2010, Oracle and/or its affiliates. All rights reserved.
+  * Copyright 2015, Joyent, Inc. All rights reserved.
   */
  
  /*
   * Indirect console driver for Sun.
   *
*** 51,60 ****
--- 52,62 ----
  #include <sys/taskq.h>
  #include <sys/log.h>
  #include <sys/vnode.h>
  #include <sys/uio.h>
  #include <sys/stat.h>
+ #include <sys/limits.h>
  
  #include <sys/console.h>
  #include <sys/consdev.h>
  
  #include <sys/stream.h>
*** 412,429 ****
          /*
           * Output to virtual console for logging if enabled.
           */
          if (vsconsvp != NULL && vsconsvp->v_stream != NULL) {
                  struiod_t uiod;
  
                  /*
                   * strwrite modifies uio so need to make copy.
                   */
!                 (void) uiodup(uio, &uiod.d_uio, uiod.d_iov,
!                     sizeof (uiod.d_iov) / sizeof (*uiod.d_iov));
  
                  (void) strwrite(vsconsvp, &uiod.d_uio, cred);
          }
  
          if (rconsvp->v_stream != NULL)
                  return (strwrite(rconsvp, uio, cred));
          else
--- 414,441 ----
          /*
           * Output to virtual console for logging if enabled.
           */
          if (vsconsvp != NULL && vsconsvp->v_stream != NULL) {
                  struiod_t uiod;
+                 struct iovec buf[IOV_MAX_STACK];
+                 int iovlen = 0;
  
+                 if (uio->uio_iovcnt > IOV_MAX_STACK) {
+                         iovlen = uio->uio_iovcnt * sizeof (iovec_t);
+                         uiod.d_iov = kmem_alloc(iovlen, KM_SLEEP);
+                 } else {
+                         uiod.d_iov = buf;
+                 }
+ 
                  /*
                   * strwrite modifies uio so need to make copy.
                   */
!                 (void) uiodup(uio, &uiod.d_uio, uiod.d_iov, uio->uio_iovcnt);
  
                  (void) strwrite(vsconsvp, &uiod.d_uio, cred);
+                 if (iovlen != 0)
+                         kmem_free(uiod.d_iov, iovlen);
          }
  
          if (rconsvp->v_stream != NULL)
                  return (strwrite(rconsvp, uio, cred));
          else