UNDERRUN error for 8270/ 8260

II am working with 8270 Motorola processor which has QNX 6.0. I am
using the Network driver code which I got from QNX BSP which we
modified as per our board requirement. I want to use all 3 available
FCC channels.
I am facing the UNDERRUN error again and again on FCC channel.
Overall this error comes for any FCC on different boards.
But normally any one or two ports does not work.
If any FCC works It works consistently.
If it fails because of underrun It shows consistent failure.
Ping works fine on any FCC. But if I try to Telnet it gives UNDERRUN. I
think problem is when I try to send only one BD.

Please send your view how to prevent FCC for UNDERRUN
1)	BD and data is on 60X bus SDRAM
2)	I tried to put BD on DPRAM but result is same

vikrantb@kpitcummins.com wrote:
> II am working with 8270 Motorola processor which has QNX 6.0. I am
> using the Network driver code which I got from QNX BSP which we
> modified as per our board requirement. I want to use all 3 available
> FCC channels.
> I am facing the UNDERRUN error again and again on FCC channel.
> Overall this error comes for any FCC on different boards.
> But normally any one or two ports does not work.
> If any FCC works It works consistently.
> If it fails because of underrun It shows consistent failure.
> Ping works fine on any FCC. But if I try to Telnet it gives UNDERRUN. I
> think problem is when I try to send only one BD.
>
> Please send your view how to prevent FCC for UNDERRUN
> 1)	BD and data is on 60X bus SDRAM
> 2)	I tried to put BD on DPRAM but result is same

Apparently you get the underrun when the packet size is larger,
i.e. the driver overhead is too much for the link speed.
Could be something else, of course - I am not familiar with
your board or driver etc.

Dimiter

------------------------------------------------------
Dimiter Popoff               Transgalactic Instruments

http://www.tgi-sci.com
------------------------------------------------------

If it is because of diver overhead it sould not work for any board but
it works fine in some FCC boards with same code and driver.