diff --git a/board/common/rootfs/usr/libexec/infix/has-quirk b/board/common/rootfs/usr/libexec/infix/has-quirk
index 4f9a9bbc8..7dc24d91d 100755
--- a/board/common/rootfs/usr/libexec/infix/has-quirk
+++ b/board/common/rootfs/usr/libexec/infix/has-quirk
@@ -1,12 +1,49 @@
-#!/bin/sh
+#!/bin/bash
+
+IFQUIRKSFILE=${IFQUIRKSFILE:-/etc/product/interface-quirks.json}
+
 if [ $# -lt 2 ]; then
         echo "usage: $0 <quirk-name> <ifname>"
         exit 1
 fi
+
 quirk=$1
 ifname=$2
-if [ -f "/etc/product/interface-quirks.json" ]; then
-        echo "$(jq -r --arg iface "$ifname" --arg quirk "$quirk" '.[$iface][$quirk] // "false"' /etc/product/interface-quirks.json)"
-else
-        echo "false"
-fi
+
+[ -f "$IFQUIRKSFILE" ] || { echo false && exit; }
+
+match()
+{
+    jq -e  \
+       --arg quirk "$quirk" --arg pattern "$1" \
+       '.[$pattern][$quirk]' "$IFQUIRKSFILE" >/dev/null || return
+
+    echo true
+    exit 0
+}
+
+ethtoolmatch()
+{
+    local pattern="${1#@ethtool:}"
+
+    grep -qFxvf \
+	 <(ethtool -i "$ifname") \
+	 <(echo -n "$pattern" | awk -v FS="=" -v RS=";" '{ printf("%s: %s\n", $1, $2); }') \
+	&& return
+
+    match "@ethtool:$pattern"
+}
+
+
+for pattern in $(jq -r 'keys[]' "$IFQUIRKSFILE"); do
+    case "$pattern" in
+	@ethtool:*)
+	    ethtoolmatch "$pattern"
+	    ;;
+	"$ifname")
+	    match "$ifname"
+	    ;;
+    esac
+done
+
+echo "false"
diff --git a/board/common/rootfs/usr/libexec/infix/init.d/20-nameif b/board/common/rootfs/usr/libexec/infix/init.d/20-nameif
index 330392599..0356ce103 100755
--- a/board/common/rootfs/usr/libexec/infix/init.d/20-nameif
+++ b/board/common/rootfs/usr/libexec/infix/init.d/20-nameif
@@ -34,6 +34,12 @@ ports=$(devlink -j port | jq -r '.port[]
 				 | select(.flavour == "physical")
 				 | .netdev')
 for iface in $ports; do
+	# On systems with multiple switch trees, a port may be _both_
+	# a physical port, registered with devlink, _and_ a DSA
+	# port. In those cases, hold on to our initial "internal"
+	# classification.
+	[ $(ip -j link show dev "$iface" | jq -r '.[0].group') = internal ] && continue
+
 	ip link set "$iface" group port
 done
 
diff --git a/src/confd/src/ietf-interfaces.c b/src/confd/src/ietf-interfaces.c
index 28045ff05..db017cc39 100644
--- a/src/confd/src/ietf-interfaces.c
+++ b/src/confd/src/ietf-interfaces.c
@@ -17,18 +17,8 @@
 
 bool iface_has_quirk(const char *ifname, const char *quirkname)
 {
-	struct json_t *iface, *quirk;
-
-	if (!confd.ifquirks)
-		return false;
-
-	iface = json_object_get(confd.ifquirks, ifname);
-	if (!iface)
-		return false;
-
-	quirk = json_object_get(iface, quirkname);
-
-	return quirk ? json_is_true(quirk) : false;
+	return systemf("[ $(/usr/libexec/infix/has-quirk %s %s) = true ]",
+		       quirkname, ifname) == 0;
 }
 
 static bool iface_is_phys(const char *ifname)