Hardware lock-in cleanup: ice RX counter set and by-driver map collapsed to the single ixgbe nicRxFields list (newNICPoller drops its redundant driver gate), checkCoalesce loses the try-tx-then-EINVAL fallback and sets rx-usecs shared with tx as the one path, ice-attributed comments neutralized, dead errs.total removed with its redundant test assertion; ice counter reference set recorded in docs/nics/e810; verified on hardware (20.00G, zero errors, ECD 41m)

system.go

@@ -59,9 +59,7 @@ func rxRings(fd int, ifname string) (uint64, error) {
 	return nfc.data, nil
 }
 
-// Returns the installed rule locations and the total filter capacity. ice
-// only honours filters near the top of that range, which is why ethtool's own
-// rule manager allocates downwards from the end.
+// Returns the installed rule locations and the total filter capacity.
 func allRuleLocations(fd int, ifname string) ([]uint32, uint32, error) {
 	cnt := ethtoolRxnfc{cmd: ethtoolGRXCLSRLCNT}
 	if err := ethtoolCall(fd, ifname, unsafe.Pointer(&cnt)); err != nil {
@@ -111,7 +109,8 @@ func deleteRule(fd int, ifname string, loc uint32) error {
 	return ethtoolCall(fd, ifname, unsafe.Pointer(&nfc))
 }
 
-// ice rejects RX_CLS_LOC_ANY, so the caller must supply a free location.
+// RX_CLS_LOC_ANY is not honoured here, so the caller supplies a free location,
+// allocated downward from the top to match ethtool's own rule manager.
 func insertEtherRule(fd int, ifname string, ethType uint16, queue uint64, loc uint32) error {
 	nfc := ethtoolRxnfc{cmd: ethtoolSRXCLSRLINS}
 	nfc.fs.flowType = etherFlow
@@ -589,7 +588,10 @@ func checkLinkUp(fd int, ifname string) checkResult {
 	return res
 }
 
-func checkCoalesce(fd int, ifname string, rxUsecs, txUsecs uint32) checkResult {
+// ixgbe runs mixed rx/tx interrupt vectors — one moderation value per vector,
+// so rx-usecs covers both, a tx-specific value is rejected, and get reports
+// the tx side as zero.
+func checkCoalesce(fd int, ifname string, usecs uint32) checkResult {
 	res := checkResult{item: ifname + " coalesce"}
 	ec, err := getCoalesce(fd, ifname)
 	if err != nil {
@@ -597,49 +599,28 @@ func checkCoalesce(fd int, ifname string, rxUsecs, txUsecs uint32) checkResult {
 		return res
 	}
 	desc := func(e ethtoolCoalesce) string {
-		return fmt.Sprintf("adaptive rx=%d tx=%d rx-usecs=%d tx-usecs=%d",
-			e.useAdaptiveRxCoalesce, e.useAdaptiveTxCoalesce, e.rxCoalesceUsecs, e.txCoalesceUsecs)
+		return fmt.Sprintf("adaptive rx=%d tx=%d rx-usecs=%d shared with tx",
+			e.useAdaptiveRxCoalesce, e.useAdaptiveTxCoalesce, e.rxCoalesceUsecs)
 	}
-	settled := func(e ethtoolCoalesce, tx uint32) bool {
-		return e.useAdaptiveRxCoalesce == 0 && e.useAdaptiveTxCoalesce == 0 &&
-			e.rxCoalesceUsecs == rxUsecs && e.txCoalesceUsecs == tx
-	}
-	if settled(ec, txUsecs) {
+	if ec.useAdaptiveRxCoalesce == 0 && ec.useAdaptiveTxCoalesce == 0 &&
+		ec.rxCoalesceUsecs == usecs && ec.txCoalesceUsecs == 0 {
 		res.state = desc(ec)
 		return res
 	}
 	was := desc(ec)
-	set := func(tx uint32) error {
-		s := ec
-		s.cmd = unix.ETHTOOL_SCOALESCE
-		s.useAdaptiveRxCoalesce = 0
-		s.useAdaptiveTxCoalesce = 0
-		s.rxCoalesceUsecs = rxUsecs
-		s.txCoalesceUsecs = tx
-		return ethtoolCall(fd, ifname, unsafe.Pointer(&s))
-	}
-	err = set(txUsecs)
-	// A driver running mixed rx/tx vectors has one moderation value per
-	// vector and rejects a tx-specific one: rx-usecs covers both, and get
-	// reports the tx side as zero.
-	if err == unix.EINVAL {
-		if settled(ec, 0) {
-			res.state = desc(ec) + " (tx shares rx)"
-			return res
-		}
-		if err = set(0); err == nil {
-			res.fixed = true
-			res.state = fmt.Sprintf("was %s, now adaptive off rx-usecs=%d shared with tx", was, rxUsecs)
-			return res
-		}
-	}
-	if err != nil {
+	s := ec
+	s.cmd = unix.ETHTOOL_SCOALESCE
+	s.useAdaptiveRxCoalesce = 0
+	s.useAdaptiveTxCoalesce = 0
+	s.rxCoalesceUsecs = usecs
+	s.txCoalesceUsecs = 0
+	if err := ethtoolCall(fd, ifname, unsafe.Pointer(&s)); err != nil {
 		res.err = err
 		res.state = "could not set"
 		return res
 	}
 	res.fixed = true
-	res.state = fmt.Sprintf("was %s, now adaptive off rx-usecs=%d tx-usecs=%d", was, rxUsecs, txUsecs)
+	res.state = fmt.Sprintf("was %s, now adaptive off rx-usecs=%d shared with tx", was, usecs)
 	return res
 }
 
@@ -753,7 +734,7 @@ func configureSystem(ifnames []string, ethertypes []uint16) []checkResult {
 			// Ring changes reprogram the queues, so flow rules pointing at those
 			// queues have to be installed afterwards.
 			out = append(out, checkRings(fd, ifname, wantRxRing, wantTxRing))
-			out = append(out, checkCoalesce(fd, ifname, wantCoalesceUsecs, wantCoalesceUsecs))
+			out = append(out, checkCoalesce(fd, ifname, wantCoalesceUsecs))
 			out = append(out, checkFlowRules(fd, ifname, ethertypes))
 		}
 		return out