Index: share/mk/bsd.mkopt.mk
===================================================================
--- share/mk/bsd.mkopt.mk
+++ share/mk/bsd.mkopt.mk
@@ -58,3 +58,12 @@
 .endif # !defined(MK_${var})
 .endfor
 .undef __DEFAULT_NO_OPTIONS
+
+#
+# MK_* options which are always no, usually because they are
+# unsupported/badly broken on this architecture.
+#
+.for var in ${__ALWAYS_NO_OPTIONS}
+MK_${var}:=	no
+.endfor
+.undef __ALWAYS_NO_OPTIONS
Index: sys/conf/kern.opts.mk
===================================================================
--- sys/conf/kern.opts.mk
+++ sys/conf/kern.opts.mk
@@ -48,6 +48,34 @@
     NAND \
     OFED
 
+# Options that cannot be turned on this architecture, usually because
+# of compilation or other issues so severe it cannot be used even
+# on an experimental basis
+__ALWAYS_NO_OPTIONS=
+
+# Things that don't work based on the CPU
+.if ${MACHINE_CPUARCH} == "arm"
+__ALWAYS_NO_OPTIONS+= CDDL ZFS
+.endif
+
+.if ${MACHINE_CPUARCH} == "mips"
+__ALWAYS_NO_OPTIONS+= CDDL ZFS
+.endif
+
+.if ${MACHINE_CPUARCH} == "powerpc" && ${MACHINE_ARCH} != "powerpc64"
+__ALWAYS_NO_OPTIONS+= ZFS
+.endif
+
+# Things that don't work because the kernel doesn't have the support
+# for them.
+.if ${MACHINE} != "i386"
+__ALWAYS_NO_OPTIONS+= EISA
+.endif
+
+.if ${MACHINE} != "i386" && ${MACHINE} != "amd64"
+__ALWAYS_NO_OPTIONS+= OFED
+.endif
+
 # expanded inline from bsd.mkopt.mk to avoid share/mk dependency
 
 # Those that default to yes
@@ -83,6 +111,16 @@
 .undef __DEFAULT_NO_OPTIONS
 
 #
+# MK_* options which are always no, usually because they are
+# unsupported/badly broken on this architecture.
+#
+.for var in ${__ALWAYS_NO_OPTIONS}
+MK_${var}:=	no
+.endfor
+.undef __ALWAYS_NO_OPTIONS
+#end of bsd.mkopt.mk expanded inline.
+
+#
 # MK_*_SUPPORT options which default to "yes" unless their corresponding
 # MK_* variable is set to "no".
 #
@@ -104,6 +142,3 @@
 .endif
 .endif
 .endfor
-
-
-