Hello, It concerns packet sending routines in 8139too.c driver (kernel:2.4.20). I am trying to find what happens exactly AFTER rtl8139_start_xmit() is called, when the packet is being forwarded through linux router. Which routine is called right after rtl8139_start_xmit() ( is this rtl8139_tx_interrupt ?) ?? I would like to know exact code path of packet going out of router interface, if possible ;) . Underneath there is snippet of code taken from http://lxr.linux.no/source/drivers/net/8139too.c. [...] - means that this part of code is cut for sake of clarity static int rtl8139_start_xmit (struct sk_buff *skb, struct net_device *dev) { [...] if (likely(len < TX_BUF_SIZE)) { skb_copy_and_csum_dev(skb, tp->tx_buf[entry]); <<-- what exactly happens here ?? // is the packet data being copied to kernel memory buffer? // what happens with packet data afterwards...??? dev_kfree_skb(skb); } else { dev_kfree_skb(skb); tp->stats.tx_dropped++; return 0; } [...] } What happens after skb_copy_and_csum_dev(skb, tp->tx_buf[entry]); and before tx_interrupt() being called ???? And what happens with packet data DURING tx_interrupt() execution? Is this being copied from kernel memory buffer into NIC memory? or is this transmitted into the network, so when tx_interrupt finishes the packet is already gone from the interface??? How the packet data are kept inside NIC: is there a small memory buffer or so? while (tx_left > 0) { int entry = dirty_tx % NUM_TX_DESC; int txstatus; txstatus = RTL_R32 (TxStatus0 + (entry * sizeof (u32))); [...] } else { if (txstatus & TxUnderrun) { [...] } tp->stats.collisions += (txstatus >> 24) & 15; tp->stats.tx_bytes += txstatus & 0x7ff; tp->stats.tx_packets++; // <- ONE packet has been actually sent, right? // how many packet can be stored inside NIC simultaneously } dirty_tx++; tx_left--; } I will be grateful for the explanation of this questions!! regards Adam F. - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
