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On Mon, Nov 21, 2005 at 05:02:41PM -0800, Jeff Rizzo wrote:
> In attempting to diagnose why I'm having jumbo-frame problems with a wm
> interface on my G4/466 running -current (~24h old), I tried compiling a
> kernel with "options MCLSHIFT=3D13", in hopes it would allow me to ping
> across the jumbo-frame link with packets larger than 2002 bytes.
>=20
> However, upon booting a kernel which is basically GENERIC with "options
> MCLSHIFT=3D13", the boot hangs thusly:
>=20
> Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
>     The NetBSD Foundation, Inc.  All rights reserved.
> Copyright (c) 1982, 1986, 1989, 1991, 1993
>     The Regents of the University of California.  All rights reserved.
>=20
> NetBSD 3.99.11 (GENERIC.MCL) #2: Mon Nov 21 16:44:55 PST 2005
>         riz@grendel:/usr/src/sys/arch/macppc/compile/GENERIC.MCL
> total memory =3D 1024 MB
> avail memory =3D 987 MB
>=20
>=20
> ...then nothing.  A kernel with MCLSHIFT=3D12 seems to boot and work OK
> (although it doesn't fix my jumbo frame issue - on a link with MTU 4500,
> I still can't get ping packets larger than 2002 bytes across!  "cksum:
> out of data" from every packet)

I realize this reply is late in coming. Please try Jason's recent fix to=20
wm (you want rev 1.111). It should fix this issue.

The problem is that the old code botched the calculation of jumbo lengths.=
=20
It would add the first segment twice and not add the last. So for a frame=
=20
that shows up as:

2048, 2048, 2048, 2048, 822

you'd get 10240 bytes, not 9014.

Take care,

Bill


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