Index: sys/arch/amd64/amd64/machdep.c
===================================================================
RCS file: /cvsroot/src/sys/arch/amd64/amd64/machdep.c,v
retrieving revision 1.243
diff -u -r1.243 machdep.c
--- sys/arch/amd64/amd64/machdep.c	23 Dec 2016 07:15:27 -0000	1.243
+++ sys/arch/amd64/amd64/machdep.c	26 Dec 2016 11:19:10 -0000
@@ -1468,30 +1468,39 @@
 static void
 init_x86_64_msgbuf(void)
 {
-        /* Message buffer is located at end of core. */
-	psize_t reqsz = round_page(MSGBUFSIZE);
-	psize_t sz = 0;
-
-	for (sz = 0; sz < reqsz; sz += PAGE_SIZE) {
-		paddr_t stolenpa;
-
-		if (!uvm_page_physget(&stolenpa))
-			break;
-
-		if (stolenpa == (msgbuf_p_seg[msgbuf_p_cnt].paddr
-			+ PAGE_SIZE)) {
-			/* contiguous: append it to current buf alloc */
-			msgbuf_p_seg[msgbuf_p_cnt].sz += PAGE_SIZE;
-		} else  {
-			/* non-contiguous: start a new msgbuf seg */
-			msgbuf_p_seg[msgbuf_p_cnt].sz = PAGE_SIZE;
-			msgbuf_p_seg[msgbuf_p_cnt++].paddr = stolenpa;
-		}
+	/* Message buffer is located at end of core. */
+	psize_t sz = round_page(MSGBUFSIZE);
+	psize_t reqsz = sz;
+	uvm_physseg_t x;
+		
+ search_again:
+	x = uvm_physseg_get_last();
+	
+	/* Shrink so it'll fit in the last segment. */
+	if (uvm_physseg_get_avail_end(x) - uvm_physseg_get_avail_start(x) < atop(sz))
+		sz = ctob(uvm_physseg_get_avail_end(x) - uvm_physseg_get_avail_start(x));
+
+	uvm_physseg_unplug(uvm_physseg_get_end(x) - atop(sz), atop(sz));
+	msgbuf_p_seg[msgbuf_p_cnt].sz = sz;
+        msgbuf_p_seg[msgbuf_p_cnt++].paddr = ctob(uvm_physseg_get_avail_end(x));
+
+	/* Now find where the new avail_end is. */
+	avail_end = ctob(uvm_physseg_get_avail_end(x));
+
+	if (sz == reqsz)
+		return;
+
+	reqsz -= sz;
+
+	if (msgbuf_p_cnt == VM_PHYSSEG_MAX) {
+		/* No more segments available, bail out. */
+		printf("WARNING: MSGBUFSIZE (%zu) too large, using %zu.\n",
+		    (size_t)MSGBUFSIZE, (size_t)(MSGBUFSIZE - reqsz));
+		return;
 	}
 
-	if (sz != reqsz)
-		printf("%s: could only allocate %ld bytes of requested %ld bytes\n",
-		    __func__, sz, reqsz);
+	sz = reqsz;
+	goto search_again;
 }
 
 static void