diff --git a/sys/sys/pipe.h b/sys/sys/pipe.h
new file mode 100644
index 000000000000..176224bd4761
--- /dev/null
+++ b/sys/sys/pipe.h
@@ -0,0 +1,111 @@
+/*
+ * Copyright (c) 1996 John S. Dyson
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice immediately at the beginning of the file, without modification,
+ *    this list of conditions, and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Absolutely no warranty of function or purpose is made by the author
+ *    John S. Dyson.
+ * 4. This work was done expressly for inclusion into FreeBSD.  Other use
+ *    is allowed if this notation is included.
+ * 5. Modifications may be freely made to this file if the above conditions
+ *    are met.
+ *
+ * $FreeBSD: src/sys/sys/pipe.h,v 1.17 2001/01/09 04:33:48 wollman Exp $
+ */
+
+#ifndef _SYS_PIPE_H_
+#define _SYS_PIPE_H_
+
+#ifndef _KERNEL
+#include <sys/time.h>			/* for struct timespec */
+#include <sys/selinfo.h>		/* for struct selinfo */
+#include <vm/vm.h>			/* for vm_page_t */
+#include <machine/param.h>		/* for PAGE_SIZE */
+#endif
+
+/*
+ * Pipe buffer size, keep moderate in value, pipes take kva space.
+ */
+#ifndef PIPE_SIZE
+#define PIPE_SIZE	16384
+#endif
+
+#ifndef BIG_PIPE_SIZE
+#define BIG_PIPE_SIZE	(64*1024)
+#endif
+
+/*
+ * PIPE_MINDIRECT MUST be smaller than PIPE_SIZE and MUST be bigger
+ * than PIPE_BUF.
+ */
+#ifndef PIPE_MINDIRECT
+#define PIPE_MINDIRECT	8192
+#endif
+
+#define PIPENPAGES	(BIG_PIPE_SIZE / PAGE_SIZE + 1)
+
+/*
+ * Pipe buffer information.
+ * Separate in, out, cnt are used to simplify calculations.
+ * Buffered write is active when the buffer.cnt field is set.
+ */
+struct pipebuf {
+	u_int	cnt;		/* number of chars currently in buffer */
+	u_int	in;		/* in pointer */
+	u_int	out;		/* out pointer */
+	u_int	size;		/* size of buffer */
+	caddr_t	buffer;		/* kva of buffer */
+	struct	vm_object *object;	/* VM object containing buffer */
+};
+
+/*
+ * Information to support direct transfers between processes for pipes.
+ */
+struct pipemapping {
+	vm_offset_t	kva;		/* kernel virtual address */
+	vm_size_t	cnt;		/* number of chars in buffer */
+	vm_size_t	pos;		/* current position of transfer */
+	int		npages;		/* number of pages */
+	vm_page_t	ms[PIPENPAGES];	/* pages in source process */
+};
+
+/*
+ * Bits in pipe_state.
+ */
+#define PIPE_ASYNC	0x004	/* Async? I/O. */
+#define PIPE_WANTR	0x008	/* Reader wants some characters. */
+#define PIPE_WANTW	0x010	/* Writer wants space to put characters. */
+#define PIPE_WANT	0x020	/* Pipe is wanted to be run-down. */
+#define PIPE_SEL	0x040	/* Pipe has a select active. */
+#define PIPE_EOF	0x080	/* Pipe is in EOF condition. */
+#define PIPE_LOCK	0x100	/* Process has exclusive access to pointers/data. */
+#define PIPE_LWANT	0x200	/* Process wants exclusive access to pointers/data. */
+#define PIPE_DIRECTW	0x400	/* Pipe direct write active. */
+#define PIPE_DIRECTOK	0x800	/* Direct mode ok. */
+
+/*
+ * Per-pipe data structure.
+ * Two of these are linked together to produce bi-directional pipes.
+ */
+struct pipe {
+	struct	pipebuf pipe_buffer;	/* data storage */
+	struct	pipemapping pipe_map;	/* pipe mapping for direct I/O */
+	struct	selinfo pipe_sel;	/* for compat with select */
+	struct	timespec pipe_atime;	/* time of last access */
+	struct	timespec pipe_mtime;	/* time of last modify */
+	struct	timespec pipe_ctime;	/* time of status change */
+	struct	sigio *pipe_sigio;	/* information for async I/O */
+	struct	pipe *pipe_peer;	/* link with other direction */
+	u_int	pipe_state;		/* pipe status info */
+	int	pipe_busy;		/* busy flag, mostly to handle rundown sanely */
+};
+
+#endif /* !_SYS_PIPE_H_ */