support building a single packet out of multiple rx descriptors.

rge is a bit like intel nics where you can put small mbufs on the
rx ring and it will chain them together to make a jumbo packet.
except unlike intel you can use any sized mbufs for the rx descriptors.

this adds the handling of these packets to the rx path. we're still
putting 9k frames on the ring though.

1 files changed, 38 insertions, 9 deletions

diff --git a/sys/dev/pci/if_rge.c b/sys/dev/pci/if_rge.c
index 01eae86de51..44ce8f0d7c1 100644
--- a/sys/dev/pci/if_rge.c
+++ b/sys/dev/pci/if_rge.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_rge.c,v 1.31 2024/08/21 00:56:58 dlg Exp $	*/
+/*	$OpenBSD: if_rge.c,v 1.32 2024/08/21 01:12:52 dlg Exp $	*/
 
 /*
  * Copyright (c) 2019, 2020, 2023, 2024
@@ -883,6 +883,12 @@ rge_stop(struct ifnet *ifp)
 	ifq_barrier(&ifp->if_snd);
 	ifq_clr_oactive(&ifp->if_snd);
 
+	if (q->q_rx.rge_head != NULL) {
+		m_freem(q->q_rx.rge_head);
+		q->q_rx.rge_head = NULL;
+		q->q_rx.rge_tail = &q->q_rx.rge_head;
+	}
+
 	/* Free the TX list buffers. */
 	for (i = 0; i < RGE_TX_LIST_CNT; i++) {
 		if (q->q_tx.rge_txq[i].txq_mbuf != NULL) {
@@ -1193,6 +1199,8 @@ rge_rx_list_init(struct rge_queues *q)
 	memset(q->q_rx.rge_rx_list, 0, RGE_RX_LIST_SZ);
 
 	q->q_rx.rge_rxq_prodidx = q->q_rx.rge_rxq_considx = 0;
+	q->q_rx.rge_head = NULL;
+	q->q_rx.rge_tail = &q->q_rx.rge_head;
 
 	if_rxr_init(&q->q_rx.rge_rx_ring, 32, RGE_RX_LIST_CNT - 1);
 	rge_fill_rx_ring(q);
@@ -1244,7 +1252,7 @@ rge_rxeof(struct rge_queues *q)
 	struct rge_rx_desc *cur_rx;
 	struct rge_rxq *rxq;
 	uint32_t rxstat, extsts;
-	int i, total_len, rx = 0;
+	int i, mlen, rx = 0;
 	int cons;
 
 	i = cons = q->q_rx.rge_rxq_considx;
@@ -1274,23 +1282,44 @@ rge_rxeof(struct rge_queues *q)
 		if_rxr_put(rxr, 1);
 		rx = 1;
 
-		total_len = rxstat & RGE_RDCMDSTS_FRAGLEN;
+		if (ISSET(rxstat, RGE_RDCMDSTS_SOF)) {
+			if (q->q_rx.rge_head != NULL) {
+				ifp->if_ierrors++;
+				m_freem(q->q_rx.rge_head);
+				q->q_rx.rge_tail = &q->q_rx.rge_head;
+			}
 
-		/* We only handle a packet per rx descriptor at the moment */
-		if ((rxstat & (RGE_RDCMDSTS_SOF | RGE_RDCMDSTS_EOF)) !=
-		    (RGE_RDCMDSTS_SOF | RGE_RDCMDSTS_EOF)) {
-			ifp->if_ierrors++;
+			m->m_pkthdr.len = 0;
+		} else if (q->q_rx.rge_head == NULL) {
 			m_freem(m);
 			continue;
-		}
+		} else
+			CLR(m->m_flags, M_PKTHDR);
+
+		*q->q_rx.rge_tail = m;
+		q->q_rx.rge_tail = &m->m_next;
+
+		mlen = rxstat & RGE_RDCMDSTS_FRAGLEN;
+		m->m_len = mlen;
+
+		m = q->q_rx.rge_head;
+		m->m_pkthdr.len += mlen;
 
 		if (rxstat & RGE_RDCMDSTS_RXERRSUM) {
 			ifp->if_ierrors++;
 			m_freem(m);
+			q->q_rx.rge_head = NULL;
+			q->q_rx.rge_tail = &q->q_rx.rge_head;
 			continue;
 		}
 
-		m->m_pkthdr.len = m->m_len = (total_len - ETHER_CRC_LEN);
+		if (!ISSET(rxstat, RGE_RDCMDSTS_EOF))
+			continue;
+
+		q->q_rx.rge_head = NULL;
+		q->q_rx.rge_tail = &q->q_rx.rge_head;
+
+		m_adj(m, -ETHER_CRC_LEN);
 
 		extsts = letoh32(cur_rx->hi_qword1.rx_qword4.rge_extsts);