diff --git a/include/zfs/vdev_impl.h b/include/zfs/vdev_impl.h
new file mode 100644
index 0000000..3aa646e
--- /dev/null
+++ b/include/zfs/vdev_impl.h
@@ -0,0 +1,70 @@
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 1999,2000,2001,2002,2003,2004  Free Software Foundation, Inc.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+/*
+ * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+#ifndef _SYS_VDEV_IMPL_H
+#define	_SYS_VDEV_IMPL_H
+
+#define	VDEV_SKIP_SIZE		(8 << 10)
+#define	VDEV_BOOT_HEADER_SIZE	(8 << 10)
+#define	VDEV_PHYS_SIZE		(112 << 10)
+#define	VDEV_UBERBLOCK_RING	(128 << 10)
+
+/* ZFS boot block */
+#define	VDEV_BOOT_MAGIC		0x2f5b007b10cULL
+#define	VDEV_BOOT_VERSION	1		/* version number	*/
+
+typedef struct vdev_boot_header {
+	uint64_t	vb_magic;		/* VDEV_BOOT_MAGIC	*/
+	uint64_t	vb_version;		/* VDEV_BOOT_VERSION	*/
+	uint64_t	vb_offset;		/* start offset	(bytes) */
+	uint64_t	vb_size;		/* size (bytes)		*/
+	char		vb_pad[VDEV_BOOT_HEADER_SIZE - 4 * sizeof(uint64_t)];
+} vdev_boot_header_t;
+
+typedef struct vdev_phys {
+	char		vp_nvlist[VDEV_PHYS_SIZE - sizeof(zio_eck_t)];
+	zio_eck_t	vp_zbt;
+} vdev_phys_t;
+
+typedef struct vdev_label {
+	char		vl_pad[VDEV_SKIP_SIZE];			/*   8K	*/
+	vdev_boot_header_t vl_boot_header;			/*   8K	*/
+	vdev_phys_t	vl_vdev_phys;				/* 112K	*/
+	char		vl_uberblock[VDEV_UBERBLOCK_RING];	/* 128K	*/
+} vdev_label_t;							/* 256K total */
+
+/*
+ * Size and offset of embedded boot loader region on each label.
+ * The total size of the first two labels plus the boot area is 4MB.
+ */
+#define	VDEV_BOOT_OFFSET	(2 * sizeof(vdev_label_t))
+#define	VDEV_BOOT_SIZE		(7ULL << 19)			/* 3.5M	*/
+
+/*
+ * Size of label regions at the start and end of each leaf device.
+ */
+#define	VDEV_LABEL_START_SIZE	(2 * sizeof(vdev_label_t) + VDEV_BOOT_SIZE)
+#define	VDEV_LABEL_END_SIZE	(2 * sizeof(vdev_label_t))
+#define	VDEV_LABELS		4
+
+#endif	/* _SYS_VDEV_IMPL_H */