ethtool failure with tulip 21143

[Stefan Jeglinski]

>  >How "broken" is it? With the card in the 6500, the tulip driver sort
>>of works, sometimes. The only error message I get out of it ever is
>>
>>Internal fault: The skbuff addresses do not match in tulip_rx [plus hex
>>output]
>
>Which match my idea about broken cache coherency on 6400/6500 machines
>and possibly other derivatives (5x00 ?).

A long time ago (2.2.13 or so), I could not use another card on the
6500 for very long with the de4x5 driver as well. At that time, Paul
provided a patch for the de4x5 driver which fixed the problem. He
also described the issue as a cache coherency problem.

>de4x5 has a tweak to align descriptors so that only one exist per
>cache line. This solved the problem for some 6400 users, but
>that tweak must be enabled by hacking the driver a bit.

Well, I wonder if that was the fix that Paul put in. Some time ago
(early 2.4) I tried the de4x5 driver with this Farallon 10/100 card
but it worked even more poorly than the tulip driver of that time did.


>Try defining CACHE_ALIGN to CAL_32LONG, and DESC_ALIGN to u32 dummy[4]
>(as in the commented out example).

I will look at the de4x5 code again and try this. It's all vaguely
familiar to me... Thanks much!


Stefan Jeglinski


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