In some mail from Luigi Rizzo, sie said:
> From owner-freebsd-hackers@freefall.freebsd.org Wed Feb 19 22:40:03 EDT 1997
> From: Luigi Rizzo <luigi@labinfo.iet.unipi.it>
> Message-Id: <199702191030.LAA09311@labinfo.iet.unipi.it>
> Subject: if_de bug found!
> To: matt@lkg.dec.com (Matt Thomas)
> Date: Wed, 19 Feb 1997 11:30:42 +0100 (MET)
> Cc: hackers@freebsd.org, dg@freebsd.org
> In-Reply-To: <3.0.32.19970215162211.0068f3e0@netrix.lkg.dec.com> from "Matt Thomas" at Feb 15, 97 04:28:37 pm
> X-Mailer: ELM [version 2.4 PL23]
> Content-Type: text
> Sender: owner-hackers@freebsd.org
> X-Loop: FreeBSD.org
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> 
> After long and painful debugging I found the bug with the 21140A driver
> (if_de.c) from netbsd. The driver has a workaround for a bug of the
> 21140A when buffers overflow, and stops the receiver and resets the
> board when this occurs. This is done in the driver (around line 3230)
> by reading from CSR8 into "misses".
> 
> Matt said this is an 'extremely rare' event, on my board, though, it
> turned out to happen at the end of every interrupt... A look at
> the 21140A reference manuals (on line on the DEC site) shows that the 3
> high bits of CSR8 are set, so that they should be ignored. After doing
> this, the driver works like a charm.
> 
> Probably the correct fix is to trigger the workaround only when b16 of
> CSR8 is set. Matt ?
> 
> Thanks to Matt for writing the driver and suggesting that the event is
> rare, and to DEC for making the hardware manuals available on line.
> 
> I'll submit a PR shortly. This might be a 2.2 candidate, if the if_de
> driver in 2.2 has the same workaround. David, can you check ?
> 
> 	Thanks
> 	Luigi
> -----------------------------+--------------------------------------
> Luigi Rizzo                  |  Dip. di Ingegneria dell'Informazione
> email: luigi@iet.unipi.it    |  Universita' di Pisa
> tel: +39-50-568533           |  via Diotisalvi 2, 56126 PISA (Italy)
> fax: +39-50-568522           |  http://www.iet.unipi.it/~luigi/
> _____________________________|______________________________________
>