$NetBSD: patch-af,v 1.3 2016/12/18 22:58:34 adam Exp $

--- src/libout123/xfermem.c.orig	2016-09-26 21:20:25.000000000 +0000
+++ src/libout123/xfermem.c
@@ -36,6 +36,13 @@ void xfermem_init (txfermem **xf, size_t
 
 #ifdef HAVE_MMAP
 #  ifdef MAP_ANON
+
+#if defined(__NetBSD__) && (__NetBSD_Version__ >= 104030000)
+	if(madvise((void *)xf, (regsize - sizeof(txfermem)),
+		    MADV_SEQUENTIAL) < 0)
+		fprintf(stderr,"madvise failed, continuing anyway...\n");
+#endif
+
 	if ((*xf = (txfermem *) mmap(0, regsize, PROT_READ | PROT_WRITE,
 			MAP_ANON | MAP_SHARED, -1, 0)) == (txfermem *) -1) {
 		perror ("mmap()");
@@ -93,6 +100,10 @@ void xfermem_done (txfermem *xf)
 	   Casting to (void*) should silence compilers in case of funny
 	   prototype for munmap(). */
 	munmap ( (void*)xf, xf->size + xf->metasize + sizeof(txfermem));
+#if defined(__NetBSD__) && (__NetBSD_Version__ >= 104030000)
+	if(madvise((void *)xf, (xf->size + xf->metasize), MADV_FREE) < 0)
+		fprintf(stderr,"madvise failed, continuing anyways..\n");
+#endif
 #else
 	if (shmdt((void *) xf) == -1) {
 		perror ("shmdt()");