[eepro100] what's the state a packet in when a sending complete interrupt happens?

Donald Becker becker@scyld.com
Mon Aug 5 16:36:04 2002

On Sun, 4 Aug 2002, shigang wrote:

>      I am doing the overhead analysis for UDP/IP over ethernet. My
> testing Network controler is 82559. I meet some problem when I reading
> the driver source code (eepro100.c) in Linux kernel 2.2.17 
>     I describe the question as follows: 
> In function "speedo_start_xmit", If an sending entry's is marked as
> CmdIntr, the controler will produce an interrupt when this packet
> sending complete.

The commend on CmdIntr is "Interrupt after completion", which means
after completion of the command.  The command is defined as uploading
the packet to the Tx FIFO, not finishing the packet transmission,.

> My question is what is the means of complete? Is it
> means that the packet has been successfully put into the  ethernet OR
> just be copied from host memory into NIC send buffer? 

The only indication of most Tx errors or success is the packet
counters.  The only Tx error reported in real time is a Tx FIFO
underrun, which is an erorr transferring the packet to the NIC.

Donald Becker				becker@scyld.com
Scyld Computing Corporation		http://www.scyld.com
410 Severn Ave. Suite 210		Second Generation Beowulf Clusters
Annapolis MD 21403			410-990-9993