From a469e551a41b79b8aa9d8cb09ba995b1a2a808fb Mon Sep 17 00:00:00 2001
From: Warner Losh <imp@FreeBSD.org>
Date: Mon, 9 Feb 2015 16:03:55 +0000
Subject: [PATCH] Enforce that MK_foo options shall be either "yes" or "no" and
 nothing else.

---
 share/mk/bsd.mkopt.mk | 8 ++++++++
 sys/conf/kern.opts.mk | 8 ++++++++
 2 files changed, 16 insertions(+)

diff --git a/share/mk/bsd.mkopt.mk b/share/mk/bsd.mkopt.mk
index 46f835b86dc..9cfe1bf09d0 100644
--- a/share/mk/bsd.mkopt.mk
+++ b/share/mk/bsd.mkopt.mk
@@ -33,7 +33,11 @@ MK_${var}:=	no
 .else
 MK_${var}:=	yes
 .endif
+.else
+.if ${MK_${var}} != "yes" && ${MK_${var}} != "no"
+.error "Illegal value for MK_${var}: ${MK_${var}}"
 .endif
+.endif # !defined(MK_${var})
 .endfor
 .undef __DEFAULT_YES_OPTIONS
 
@@ -47,6 +51,10 @@ MK_${var}:=	yes
 .else
 MK_${var}:=	no
 .endif
+.else
+.if ${MK_${var}} != "yes" && ${MK_${var}} != "no"
+.error "Illegal value for MK_${var}: ${MK_${var}}"
 .endif
+.endif # !defined(MK_${var})
 .endfor
 .undef __DEFAULT_NO_OPTIONS
diff --git a/sys/conf/kern.opts.mk b/sys/conf/kern.opts.mk
index 81d91afc374..112c217e2da 100644
--- a/sys/conf/kern.opts.mk
+++ b/sys/conf/kern.opts.mk
@@ -58,7 +58,11 @@ MK_${var}:=	no
 .else
 MK_${var}:=	yes
 .endif
+.else
+.if ${MK_${var}} != "yes" && ${MK_${var}} != "no"
+.error "Illegal value for MK_${var}: ${MK_${var}}"
 .endif
+.endif # !defined(MK_${var})
 .endfor
 .undef __DEFAULT_YES_OPTIONS
 
@@ -70,7 +74,11 @@ MK_${var}:=	yes
 .else
 MK_${var}:=	no
 .endif
+.else
+.if ${MK_${var}} != "yes" && ${MK_${var}} != "no"
+.error "Illegal value for MK_${var}: ${MK_${var}}"
 .endif
+.endif # !defined(MK_${var})
 .endfor
 .undef __DEFAULT_NO_OPTIONS