diff --git a/ChangeLog b/ChangeLog
index be4173f..b929436 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2018-08-08  John Ericson  <john.ericson@obsidian.systems>
+
+	* testsuiteb/config-sub.sh (run_config_sub_idempotent): New.
+	* config.sub: Fixes to pass the testsuite.
+
 2018-08-03  John Ericson  <john.ericson@obsidian.systems>
 
 	* testsuite/config-guess.sh: Make 'rc' a local variable.
diff --git a/config.sub b/config.sub
index 52eb02e..eb33427 100755
--- a/config.sub
+++ b/config.sub
@@ -654,6 +654,8 @@ case $basic_machine in
 	leon|leon[3-9])
 		basic_machine=sparc-$basic_machine
 		;;
+	m6811-* | m68hc11-* | m6812-* | m68hc12-* | m68hcs12x-* | nvptx-* | picochip-*)
+		;;
 	m6811 | m68hc11 | m6812 | m68hc12 | m68hcs12x | nvptx | picochip)
 		basic_machine=$basic_machine-unknown
 		os=${os:-none}
@@ -664,6 +666,9 @@ case $basic_machine in
 		basic_machine=s12z-unknown
 		os=${os:-none}
 		;;
+	m9s12z-* | m68hcs12z-* | hcs12z-* | s12z-*)
+		basic_machine=s12z-`echo "$basic_machine" | sed 's/^[^-]*-//'`
+		;;
 	ms1)
 		basic_machine=mt-unknown
 		;;
@@ -674,6 +679,8 @@ case $basic_machine in
 		basic_machine=$basic_machine-unknown
 		os=${os:-none}
 		;;
+	xgate-*)
+		;;
 	xscaleeb)
 		basic_machine=armeb-unknown
 		;;
@@ -689,22 +696,26 @@ case $basic_machine in
 	  basic_machine=$basic_machine-pc
 	  ;;
 	# Recognize the basic CPU types with company name.
-	580-* \
+	1750a-* | 580-* \
 	| a29k-* \
 	| aarch64-* | aarch64_be-* \
+	| abacus-* \
 	| alpha-* | alphaev[4-8]-* | alphaev56-* | alphaev6[78]-* \
 	| alpha64-* | alpha64ev[4-8]-* | alpha64ev56-* | alpha64ev6[78]-* \
-	| alphapca5[67]-* | alpha64pca5[67]-* | arc-* | arceb-* \
-	| arm-*  | armbe-* | armle-* | armeb-* | armv*-* \
+	| alphapca5[67]-* | alpha64pca5[67]-* \
+	| am33_2.0-* \
+	| arc-* | arceb-* \
+	| arm-*  | arm[lb]e-* | arme[lb]-* | armv*-* \
 	| avr-* | avr32-* \
+	| asmjs-* \
 	| ba-* \
 	| be32-* | be64-* \
 	| bfin-* | bs2000-* \
 	| c[123]* | c30-* | [cjt]90-* | c4x-* \
 	| c8051-* | clipper-* | craynv-* | csky-* | cydra-* \
-	| d10v-* | d30v-* | dlx-* \
-	| e2k-* | elxsi-* \
-	| f30[01]-* | f700-* | fido-* | fr30-* | frv-* | fx80-* \
+	| d10v-* | d30v-* | dlx-* | dsp16xx-* \
+	| e2k-* | elxsi-* | epiphany-* \
+	| f30[01]-* | f700-* | fido-* | fr30-* | frv-* | ft32-* | fx80-* \
 	| h8300-* | h8500-* \
 	| hppa-* | hppa1.[01]-* | hppa2.0-* | hppa2.0[nw]-* | hppa64-* \
 	| hexagon-* \
@@ -714,8 +725,8 @@ case $basic_machine in
 	| le32-* | le64-* \
 	| lm32-* \
 	| m32c-* | m32r-* | m32rle-* \
-	| m68000-* | m680[012346]0-* | m68360-* | m683?2-* | m68k-* \
-	| m88110-* | m88k-* | maxq-* | mcore-* | metag-* \
+	| m5200-* | m68000-* | m680[012346]0-* | m68360-* | m683?2-* | m68k-* | v70-* | w65-* \
+	| m88110-* | m88k-* | maxq-* | mb-* | mcore-* | mep-* | metag-* \
 	| microblaze-* | microblazeel-* \
 	| mips-* | mipsbe-* | mipseb-* | mipsel-* | mipsle-* \
 	| mips16-* \
@@ -739,6 +750,7 @@ case $basic_machine in
 	| mipsr5900-* | mipsr5900el-* \
 	| mipstx39-* | mipstx39el-* \
 	| mmix-* \
+	| mn10200-* | mn10300-* \
 	| moxie-* \
 	| mt-* \
 	| msp430-* \
@@ -748,6 +760,7 @@ case $basic_machine in
 	| none-* | np1-* | ns16k-* | ns32k-* \
 	| open8-* \
 	| or1k*-* \
+	| or32-* \
 	| orion-* \
 	| pdp10-* | pdp11-* | pj-* | pjl-* | pn-* | power-* \
 	| powerpc-* | powerpc64-* | powerpc64le-* | powerpcle-* \
@@ -755,14 +768,15 @@ case $basic_machine in
 	| pyramid-* \
 	| riscv-* | riscv32-* | riscv64-* \
 	| rl78-* | romp-* | rs6000-* | rx-* \
-	| sh-* | sh[1234]-* | sh[24]a-* | sh[24]aeb-* | sh[23]e-* | sh[34]eb-* | sheb-* | shbe-* \
-	| shle-* | sh[1234]le-* | sh3ele-* | sh64-* | sh64le-* \
+	| score-* \
+	| sh-* | sh[1234]-* | sh[24]a-* | sh[24]ae[lb]-* | sh[23]e-* | she[lb]-* | sh[lb]e-* \
+	| sh[1234]e[lb]-* |  sh[12345][lb]e-* | sh3ele-* | sh64-* | sh64le-* \
 	| sparc-* | sparc64-* | sparc64b-* | sparc64v-* | sparc86x-* | sparclet-* \
 	| sparclite-* \
 	| sparcv8-* | sparcv9-* | sparcv9b-* | sparcv9v-* | sv1-* | sx*-* \
+	| spu-* \
 	| tahoe-* \
 	| tic30-* | tic4x-* | tic54x-* | tic55x-* | tic6x-* | tic80-* \
-	| tile*-* \
 	| tron-* \
 	| ubicom32-* \
 	| v850-* | v850e-* | v850e1-* | v850es-* | v850e2-* | v850e2v3-* \
@@ -1154,6 +1168,9 @@ case $basic_machine in
 	sh5el)
 		basic_machine=sh5le-unknown
 		;;
+	sh5el-*)
+		basic_machine=sh5le-`echo "$basic_machine" | sed 's/^[^-]*-//'`
+		;;
 	simso-wrs)
 		basic_machine=sparclite-wrs
 		os=vxworks
@@ -1179,6 +1196,8 @@ case $basic_machine in
 	sun386 | sun386i | roadrunner)
 		basic_machine=i386-sun
 		;;
+	tile*-*)
+		;;
 	tile*)
 		basic_machine=$basic_machine-unknown
 		os=linux-gnu
@@ -1354,7 +1373,7 @@ case $os in
 	     | amigaos* | amigados* | msdos* | newsos* | unicos* | aof* \
 	     | aos* | aros* | cloudabi* | sortix* \
 	     | nindy* | vxsim* | vxworks* | ebmon* | hms* | mvs* \
-	     | clix* | riscos* | uniplus* | iris* | rtu* | xenix* \
+	     | clix* | riscos* | uniplus* | iris* | isc* | rtu* | xenix* \
 	     | knetbsd* | mirbsd* | netbsd* \
 	     | bitrig* | openbsd* | solidbsd* | libertybsd* \
 	     | ekkobsd* | kfreebsd* | freebsd* | riscix* | lynxos* \
diff --git a/testsuite/config-sub.sh b/testsuite/config-sub.sh
index 4d01ee0..a6ac5a1 100644
--- a/testsuite/config-sub.sh
+++ b/testsuite/config-sub.sh
@@ -9,28 +9,54 @@
 # the alias expands to the expected canonical triplet.
 
 set -eu
+shopt -s lastpipe
 verbose=false
 
 run_config_sub()
 {
 	local -i rc=0
+	numtests=0
+	name="checks"
 	while read -r alias canonical ; do
 		output=$(sh -eu ../config.sub "$alias")
 		if test "$output" != "$canonical" ; then
 			echo "FAIL: $alias -> $output, but expected $canonical"
 			rc=1
 		else
-			$verbose && echo "PASS: $alias"
+			$verbose && echo "PASS: $alias -> $canonical"
 		fi
+		numtests+=1
 	done < config-sub.data
 	return $rc
 }
 
-if run_config_sub ; then
-	numtests=$(wc -l config-sub.data | cut -d' ' -f1)
-	$verbose || echo "PASS: config.sub checks ($numtests tests)"
-else
-	exit 1
-fi
+run_config_sub_idempotent()
+{
+	local -i rc=0
+	numtests=0
+	name="idempotency checks"
+	sed -r 's/\t+/\t/g' < config-sub.data | cut -f 2 | uniq | while read -r canonical ; do
+		output=$(sh -eu ../config.sub "$canonical")
+		if test "$output" != "$canonical" ; then
+			echo "FAIL: $canonical -> $output, but $canonical should map to itself"
+			rc=1
+		else
+			$verbose && echo "PASS: $canonical -> $canonical"
+		fi
+		numtests+=1
+	done
+	return $rc
+}
 
-exit 0
+declare -i rc=0 numtests
+declare name
+
+for testsuite in run_config_sub run_config_sub_idempotent ; do
+	if $testsuite; then
+		$verbose || echo "PASS: config.sub $name ($numtests tests)"
+	else
+		rc=1
+	fi
+done
+
+exit $rc