Index: lib/geom/part/gpart.8
===================================================================
--- lib/geom/part/gpart.8
+++ lib/geom/part/gpart.8
@@ -1207,7 +1207,13 @@
 GEOM class.
 The default value is shown next to each variable.
 .Bl -tag -width indent
-.It Va kern.geom.part.auto_resize: No 1
+.It Va kern.geom.part.allow_nesting : No 0
+By default, some schemes (currently BSD, BSD64 and VTOC8) do not permit
+further nested partitioning.
+This variable overrides this restriction and allows arbitrary nesting (except
+within partitions created at offset 0).
+Some schemes have their own separate checks, for which see below.
+.It Va kern.geom.part.auto_resize : No 1
 This variable controls automatic resize behavior of
 .Nm
 GEOM class.
@@ -1228,6 +1234,9 @@
 If some inconsistency is detected, the partition table will be
 rejected with a diagnostic message:
 .Sy "GEOM_PART: Integrity check failed (provider, scheme)" .
+.It Va kern.geom.part.gpt.allow_nesting : No 0
+By default the GPT scheme is allowed only at the outermost nesting level.
+This variable allows this restriction to be removed.
 .It Va kern.geom.part.ldm.debug : No 0
 Debug level of the Logical Disk Manager (LDM) module.
 This can be set to a number between 0 and 2 inclusive.
Index: sys/geom/part/g_part.c
===================================================================
--- sys/geom/part/g_part.c
+++ sys/geom/part/g_part.c
@@ -143,6 +143,10 @@
 SYSCTL_UINT(_kern_geom_part, OID_AUTO, auto_resize,
     CTLFLAG_RWTUN, &auto_resize, 1,
     "Enable auto resize");
+static u_int allow_nesting = 0;
+SYSCTL_UINT(_kern_geom_part, OID_AUTO, allow_nesting,
+    CTLFLAG_RWTUN, &allow_nesting, 0,
+    "Allow additional levels of nesting");
 
 /*
  * The GEOM partitioning class.
@@ -2271,7 +2275,13 @@
 			return;
 		if (g_handleattr_int(bp, "GEOM::fwsectors", table->gpt_sectors))
 			return;
-		if (g_handleattr_int(bp, "PART::isleaf", table->gpt_isleaf))
+		/*
+		 * allow_nesting overrides "isleaf" to false _unless_ the
+		 * provider offset is zero, since otherwise we would recurse.
+		 */
+		if (g_handleattr_int(bp, "PART::isleaf",
+			table->gpt_isleaf &&
+			(allow_nesting == 0 || entry->gpe_offset == 0)))
 			return;
 		if (g_handleattr_int(bp, "PART::depth", table->gpt_depth))
 			return;
Index: sys/geom/part/g_part_gpt.c
===================================================================
--- sys/geom/part/g_part_gpt.c
+++ sys/geom/part/g_part_gpt.c
@@ -54,6 +54,14 @@
 
 FEATURE(geom_part_gpt, "GEOM partitioning class for GPT partitions support");
 
+SYSCTL_DECL(_kern_geom_part);
+static SYSCTL_NODE(_kern_geom_part, OID_AUTO, gpt, CTLFLAG_RW, 0,
+    "GEOM_PART_GPT GUID Partition Table");
+
+static u_int allow_nesting = 0;
+SYSCTL_UINT(_kern_geom_part_gpt, OID_AUTO, allow_nesting,
+    CTLFLAG_RWTUN, &allow_nesting, 0, "Allow GPT to be nested inside other schemes");
+
 CTASSERT(offsetof(struct gpt_hdr, padding) == 92);
 CTASSERT(sizeof(struct gpt_ent) == 128);
 
@@ -652,8 +660,8 @@
 	struct g_part_gpt_table *table;
 	size_t tblsz;
 
-	/* We don't nest, which means that our depth should be 0. */
-	if (basetable->gpt_depth != 0)
+	/* Our depth should be 0 unless nesting was explicitly enabled. */
+	if (!allow_nesting && basetable->gpt_depth != 0)
 		return (ENXIO);
 
 	table = (struct g_part_gpt_table *)basetable;
@@ -815,8 +823,8 @@
 	u_char *buf;
 	int error, index, pri, res;
 
-	/* We don't nest, which means that our depth should be 0. */
-	if (table->gpt_depth != 0)
+	/* Our depth should be 0 unless nesting was explicitly enabled. */
+	if (!allow_nesting && table->gpt_depth != 0)
 		return (ENXIO);
 
 	pp = cp->provider;