[ethernet] Use standard 1500 byte MTU unless explicitly overridden

Devices that support jumbo frames will currently default to the
largest possible MTU.  This assumption is valid for virtual adapters
such as virtio-net, where the MTU must have been configured by a
system administrator, but is unsafe in the general case of a physical
adapter.

Default to the standard Ethernet MTU, unless explicitly overridden
either by the driver or via the ${netX/mtu} setting.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/drivers/net/ena.c b/src/drivers/net/ena.c
index 8d29979bbc078954ea8feb87077aea3d06455b25..0f25c0beb4ea3b2b9ea273101c4b0bd0cad1300e 100644 (file)
--- a/src/drivers/net/ena.c
+++ b/src/drivers/net/ena.c
@@ -565,6 +565,7 @@ static int ena_get_device_attributes ( struct net_device *netdev ) {
        feature = &rsp->get_feature.feature;
        memcpy ( netdev->hw_addr, feature->device.mac, ETH_ALEN );
        netdev->max_pkt_len = le32_to_cpu ( feature->device.mtu );
+       netdev->mtu = ( netdev->max_pkt_len - ETH_HLEN );
 
        DBGC ( ena, "ENA %p MAC %s MTU %zd\n",
               ena, eth_ntoa ( netdev->hw_addr ), netdev->max_pkt_len );

diff --git a/src/drivers/net/virtio-net.c b/src/drivers/net/virtio-net.c
index fe79a92c4c1b0b916a418eea76a570e4852a6d01..78ec9ac4e0be0431addcfe63ebbf1d8609a07b5d 100644 (file)
--- a/src/drivers/net/virtio-net.c
+++ b/src/drivers/net/virtio-net.c
@@ -493,6 +493,7 @@ static int virtnet_probe_legacy ( struct pci_device *pci ) {
                         &mtu, sizeof ( mtu ) );
                DBGC ( virtnet, "VIRTIO-NET %p mtu=%d\n", virtnet, mtu );
                netdev->max_pkt_len = ( mtu + ETH_HLEN );
+               netdev->mtu = mtu;
        }
 
        /* Register network device */

diff --git a/src/net/ethernet.c b/src/net/ethernet.c
index 26fdedea8e1242ef89438633f592eeb313562f8a..707bdf90508927fcd21eb1a82306a3f58f0d08de 100644 (file)
--- a/src/net/ethernet.c
+++ b/src/net/ethernet.c
@@ -269,6 +269,7 @@ struct net_device * alloc_etherdev ( size_t priv_size ) {
                netdev->ll_protocol = &ethernet_protocol;
                netdev->ll_broadcast = eth_broadcast;
                netdev->max_pkt_len = ETH_FRAME_LEN;
+               netdev->mtu = ETH_MAX_MTU;
        }
        return netdev;
 }