Experimental Physics and
Industrial Control System

David Kline <[email protected]> · Tue, 15 Feb 2011 19:27:05 -0600

this is what i do as well. the initial download is a few minutes, but after
that it's never a problem over epics (i.e. flashburner application).

----- Original Message -----
From: John Dobbins <[email protected]>
Date: Tuesday, February 15, 2011 7:00 pm
Subject: Re: Arcturus uCDimm + TFTP
To: Eric Norum <[email protected]>
Cc: EPICS Tech Talk <[email protected]>

> On 2/15/2011 4:13 PM, Eric Norum wrote:
>  > The problem is that the network stack provided by the uCDIMM 
> bootstrap has a *very* small receive queue.    If you have any 
> significant broadcast traffic on the network segment you'll start 
> losing TFTP packets resulting in massive slowdowns.
>  >
>  > Possible workarounds:
>  > 1) Burn your first application into the ColdFire using TFTP on a 
> quiet network segment -- I did this by connecting the ColdFire 
> directly to my laptop -- with only two device on the network the TFTP 
> transfers run very fast.
>  
>  That is just what I did to get around this.
>  
>  
>  > 2) From then on use the EPICS flash memory driver to update your 
> application.  The RTEMS network stack is much more robust and doesn't 
> drop packets so easily.
>  
>  I don't know about this EPICS flash memory driver. Is there something 
> I 
>  should have read?
>  
>  Thanks,
>  
>  John Dobbins
>  
>  
>  
>  
>  
>  > What's really annoying is that the bad behaviour could be fixed 
> with a small change in the bootstrap code -- once TFTP has begun, turn 
> off reception of broadcast packets in the network hardware then turn 
> reception back on when the TFTP command is terminated.   This would 
> completely fix the problem while still allowing RARP/etc. to continue 
> to work.   I suggested this to Arcturus several times, but they 
> clearly haven't fixed things yet.
>  >
>  >
>  > On Feb 15, 2011, at 1:01 PM, John Dobbins wrote:
>  >
>  >> Hello All,
>  >>
>  >> I have just built EPICS base and an example IOC for an 
> RTEMS-uC5252 target (EPICS R3.14.11, RTEMS 3.9.3), which I can say 
> went swimmingly well. However tftp problems are sucking all the fun 
> out of it. The Arcturus uCDimm comes with a TFTP server which I am 
> using with a 255.255.0.0 netmask. File transfer takes forever and 
> usually ends in a time-out error. We have some evidence that things 
> work much better on a subnet with a 255.255.255.0 mask. Can anyone 
> shed light on any of this?
>  >>
>  >> Regards,
>  >>
>  >> John Dobbins
>  >>
>  >> Cornell University
>  >
>  
>  

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System