Re: kern/34799: IP Filter does not work correctly with gem(4) when hardware chec

[Julian Coleman <jdc%coris.org.uk@localhost>]

The following reply was made to PR kern/34799; it has been noted by GNATS.

From: Julian Coleman <jdc%coris.org.uk@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: dhgutteridge%sympatico.ca@localhost
Subject: Re: kern/34799: IP Filter does not work correctly with gem(4) when 
hardware chec
Date: Mon, 28 Jan 2008 09:35:21 +0000

 Hi,
 
 >  So, either receive checksums are always broken (seems odd to me), or we
 >  are setting up the card incorrectly.   I'll see if I can spot where.
 
 Looking at this further, I thought that we should be setting the receive
 checksum offset to the end of the ethernet header, not the end of the IP
 header.  However, when I do this, the checksum part of the received data
 is still the same, but the hash value part changed.
 
 I looked at the OpenSolaris and Linux sources to see what they were doing.
 OpenSolaris sets the offset to the end of the ethernet header (so they must
 see the same bug that we're seeing) and Linux appears to ignore receive
 checksums entirely.
 
 I'm tempted to do the latter, as then we will at least work out of the box,
 rather than breaking with ipfilter.  Also, I'm pretty much out of ideas at
 this point.
 
 Thanks,
 
 J
 
 -- 
   My other computer also runs NetBSD    /        Sailing at Newbiggin
         http://www.netbsd.org/        /   http://www.newbigginsailingclub.org/