Networking: Still waiting for mbuf cluster.

[Thomas Doerfler]

Torsten,

the messages you mentioned are a typical signal, that someone (the
driver?) eats up the network buffers. Either they are dropped and not
properly returned to the free buffer pool, or they are stuck to the
transmit queue.

I saw this once, when the network driver's transmit interrupt did not
properly clean up things. You should make sure that:

- The ethernet hardware properly generates interrupts, when a buffer has
been transmitted

- The network driver makes sure that it cleans up the transmitted
buffers, even if it gets only one transmit interrupt for multiple
buffers transmitted.

- Are you possible getting transmit errors (like collision etc) in your
hardware, and the driver does not properly handle this condition?

wkr,
Thomas.


Torsten Landschoff schrieb:
> Hello List,
> 
> I ran into an interesting problem with RTEMS 4.7.99.2. I built a test
> setup with a Virtex4 FPGA and everything seems to be working.
> 
> Now I created a new FPGA design for another application. RTEMS seems to
> work fine, networking is up and I can ping the system.
> 
> Then I tried using TCP with the netdemo.exe, which basically hangs
> RTEMS. I uploaded the original design again, and interestingly, TCP
> would not work in netdemo.exe either.
> 
> At that point I remembered, that I used ttcp for testing TCP with the
> original design and uploaded that. Curiously, that is working with the
> original design.
> 
> Kind of reliefed, I uploaded the new FPGA setup and tried ttcp. There I
> get the following error message:
> 
> ttcp-t: connect
> Still waiting for mbuf cluster.
> Still waiting for mbuf cluster.
> Still waiting for mbuf cluster.
> ...
> 
> I am quite sure that something is up with the FPGA setup here, but
> perhaps somebody has some clues where to look!? Could it be related to
> cache configuration? Interestingly, ping's are still working (even flood
> ping just slows down the RTEMS console output).
> 
> Thanks for any hint, Torsten
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