From 64f441d2e53ac6ed8b4ef199e1995529d2012000 Mon Sep 17 00:00:00 2001 From: Andrey Smirnov Date: Mon, 28 Nov 2016 10:13:14 -0800 Subject: [PATCH] fsl_etsec: Pad short payloads with zeros Depending on QEMU network setup it is possible for us to receive a complete Ethernet packet that is less 64 bytes long. One such example is when QEMU is configured to use a standalone TAP device (not set to be a part of any bridge) receives and ARP packet. In cases like that we need to add more than just 4-bytes of CRC padding and ensure that our payload is at least 60 bytes long, such that, when combined with CRC padding bytes the resulting size is at least 802.3 minimum MTU bytes long (64). Failing to do that results in code in etsec_walk_rx_ring() setting BD_RX_SH which, in turn, makes corresponding Linux driver of emulated host to reject buffer as a runt packet Signed-off-by: Andrey Smirnov Signed-off-by: Jason Wang --- hw/net/fsl_etsec/rings.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/hw/net/fsl_etsec/rings.c b/hw/net/fsl_etsec/rings.c index 79d2f14..54c0127 100644 --- a/hw/net/fsl_etsec/rings.c +++ b/hw/net/fsl_etsec/rings.c @@ -474,6 +474,14 @@ static void rx_init_frame(eTSEC *etsec, const uint8_t *buf, size_t size) /* CRC padding (We don't have to compute the CRC) */ etsec->rx_padding = 4; + /* + * Ensure that payload length + CRC length is at least 802.3 + * minimum MTU size bytes long (64) + */ + if (etsec->rx_buffer_len < 60) { + etsec->rx_padding += 60 - etsec->rx_buffer_len; + } + etsec->rx_first_in_frame = 1; etsec->rx_remaining_data = etsec->rx_buffer_len; RING_DEBUG("%s: rx_buffer_len:%u rx_padding+crc:%u\n", __func__, -- 2.7.4