Added in 2002 r1.48 "sync with latest KAME [...]" along the attribute,
but nd6_free() became a global void function in 2017 r1.212.
Afaik static kernel functions are avoided to aid ddb'ugging and I
presume the "significant changes in the kernel" bits of the comment stem
from something 20 years ago no longer holding true today.
Afterall, this change has been safe for five years.
diff --git a/sys/netinet6/nd6.c b/sys/netinet6/nd6.c
index a596414a175..2e85d35c6f1 100644
--- a/sys/netinet6/nd6.c
+++ b/sys/netinet6/nd6.c
@@ -699,9 +699,6 @@ nd6_invalidate(struct rtentry *rt)
/*
* Free an nd6 llinfo entry.
- * Since the function would cause significant changes in the kernel, DO NOT
- * make it global, unless you have a strong reason for the change, and are sure
- * that the change is safe.
*/
void
nd6_free(struct rtentry *rt)
