Index: lib/geom/part/gpart.8
===================================================================
--- lib/geom/part/gpart.8
+++ lib/geom/part/gpart.8
@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd September 3, 2019
+.Dd October 30, 2019
 .Dt GPART 8
 .Os
 .Sh NAME
@@ -1260,6 +1260,14 @@
 recalculate the user-specified offset and size for alignment with the CHS
 geometry.
 Otherwise the values will be left unchanged.
+.It Va kern.geom.part.separator : No ""
+Specify an optional separator that will get inserted the GEOM name and
+partition name.
+This variable is a
+.Xr loader 8
+tunable.
+Note that setting it might break software which assumes a particular
+naming scheme.
 .El
 .Sh EXIT STATUS
 Exit status is 0 on success, and 1 if the command fails.
Index: sys/geom/part/g_part.h
===================================================================
--- sys/geom/part/g_part.h
+++ sys/geom/part/g_part.h
@@ -228,6 +228,8 @@
 
 int g_part_modevent(module_t, int, struct g_part_scheme *);
 
+extern char g_part_separator[];
+
 #define	G_PART_SCHEME_DECLARE(name)				\
     static int name##_modevent(module_t mod, int tp, void *d)	\
     {								\
Index: sys/geom/part/g_part.c
===================================================================
--- sys/geom/part/g_part.c
+++ sys/geom/part/g_part.c
@@ -147,6 +147,10 @@
 SYSCTL_UINT(_kern_geom_part, OID_AUTO, allow_nesting,
     CTLFLAG_RWTUN, &allow_nesting, 0,
     "Allow additional levels of nesting");
+char g_part_separator[MAXPATHLEN] = "";
+SYSCTL_STRING(_kern_geom_part, OID_AUTO, separator,
+    CTLFLAG_RDTUN, &g_part_separator, sizeof(g_part_separator),
+    "Partition name separator");
 
 /*
  * The GEOM partitioning class.
Index: sys/geom/part/g_part_if.m
===================================================================
--- sys/geom/part/g_part_if.m
+++ sys/geom/part/g_part_if.m
@@ -48,7 +48,7 @@
 	{
 		char buf[32];
 
-		sbuf_printf(sb, "%s%s", pfx,
+		sbuf_printf(sb, "%s%s%s", pfx, g_part_separator,
 		    G_PART_NAME(table, entry, buf, sizeof(buf)));
 	}