RTEMS 4.X.X gen68360 Ethernet Tx Reliability

[Bob Wisdom]

Thank you kindly!  Phew, an easy one to answer at last.
Maybe I can have a weekend now without worrying about new problems which
don't actually exist :)
Cheers!
Bob Wisdom

-----Original Message-----
From: jskulpin at eng01.gdds.com [mailto:jskulpin at eng01.gdds.com]
Sent: Friday, February 04, 2000 4:57 PM
To: bobwis at ascweb.co.uk
Subject: Re: RTEMS 4.X.X gen68360 Ethernet Tx Reliability

Bob Wisdom wrote:
>
> Clues and Red Herrings!
> -----------------------------------
> We have discovered that if we negate the code which attempts to skip empty
> MBUFs we can achieve reliable transmission. Obviously, one cannot allow
the
> SCC to try and send a zero length buffer, so we implemented a little
in-line
> "scatter" function which split the previous SCC TX buffer into two, thus
> filling the TX buffer which would have corresponded to the zero length
MBUF.
> Bingo, it all seems to work ok. Anyone got any ideas why? - we have sent
> hundreds of Megabytes using buffer sizes > 1500 which was impossible
before,
> it hasn't failed yet.
>
> Next problem - or maybe ignorance on my part more likely. The netdemo prog
> has a TCP test. You type "t" to start it. We set up our Linux box to act
as
> a packet dump on the discard port and we find that we can only run the
test
> every couple of minutes. If we try to repeat it too quickly we get an
error
> which says "Can't bind to socket". Is this a TCP phenomenon?
>
> Bob Wisdom
> bobwis at ascweb.co.uk

Yes.  Check into setsockopt() with SO_REUSEADDR.