Index: head/sys/conf/options
===================================================================
--- head/sys/conf/options
+++ head/sys/conf/options
@@ -640,6 +640,9 @@
 NFS_MAXDIRATTRTIMO	opt_nfs.h
 NFS_DEBUG		opt_nfs.h
 
+# TMPFS options
+TMPFS_PAGES_MINRESERVED		opt_tmpfs.h
+
 # For the Bt848/Bt848A/Bt849/Bt878/Bt879 driver
 OVERRIDE_CARD			opt_bktr.h
 OVERRIDE_TUNER			opt_bktr.h
Index: head/sys/fs/tmpfs/tmpfs.h
===================================================================
--- head/sys/fs/tmpfs/tmpfs.h
+++ head/sys/fs/tmpfs/tmpfs.h
@@ -487,7 +487,9 @@
  * Amount of memory pages to reserve for the system (e.g., to not use by
  * tmpfs).
  */
+#if !defined(TMPFS_PAGES_MINRESERVED)
 #define TMPFS_PAGES_MINRESERVED		(4 * 1024 * 1024 / PAGE_SIZE)
+#endif
 
 size_t tmpfs_mem_avail(void);
 
Index: head/sys/fs/tmpfs/tmpfs_vfsops.c
===================================================================
--- head/sys/fs/tmpfs/tmpfs_vfsops.c
+++ head/sys/fs/tmpfs/tmpfs_vfsops.c
@@ -42,6 +42,9 @@
  * memory-specific data structures and algorithms to automatically
  * allocate and release resources.
  */
+
+#include "opt_tmpfs.h"
+
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
Index: head/sys/modules/tmpfs/Makefile
===================================================================
--- head/sys/modules/tmpfs/Makefile
+++ head/sys/modules/tmpfs/Makefile
@@ -4,6 +4,6 @@
 
 KMOD=	tmpfs
 SRCS=	vnode_if.h \
-	tmpfs_vnops.c tmpfs_fifoops.c tmpfs_vfsops.c tmpfs_subr.c
+	tmpfs_vnops.c tmpfs_fifoops.c tmpfs_vfsops.c tmpfs_subr.c opt_tmpfs.h
 
 .include <bsd.kmod.mk>