QMI IPv6 crashes

Dan Williams dcbw at redhat.com
Mon Jul 21 10:28:17 PDT 2014

On Fri, 2014-06-13 at 09:41 +0200, Bjørn Mork wrote:
> Dan Williams <dcbw at redhat.com> writes:
> > On Wed, 2014-06-11 at 10:12 +0200, Bjørn Mork wrote:
> >
> >> Did you try disabling anything that might possibly send anything
> >> unexpected to the modem (SLAAC, ND, whatever)?  In theory the connection
> >> should still work with a statically assigned address, default routing
> >> out the interface and no ND.
> >
> > Haven't had time to do this yet, but I'll try to get there.  I wonder if
> > there's a good way to disable the kernel assignment of an LL address to
> > the interface, just for testing?  (though I think not...)
> No, there isn't.  AFAIK a LL address is always required for IPv6. And it
> seems the kernel will add one even if you have manually configured one
> before bringing the interface up.  That's possibly a kernel bug?
> But I believe most ND transmits are disabled by setting NOARP. And the
> rest can be avoided by tweaking the /proc/sys/net/ipv6/conf/<iface>/*
> settings.

So I tried this with the MC7750 and a Verizon IPv6-only connection.  I
set NOARP, and set router_solicitations,
mldv2_unsolicited_report_interval, mldv1_unsolicited_report_interval,
and ndisc_notify to "0" to disable them.  I also verified that with QMI
static IP configuration NetworkManager was *not* sending router
solicitations.  I then ran tcpdump on the WWAN interface to capture any
packets.  No packets were captured in two tries, and the device still
crashed with:

Src: FatalError
Dat: 00000DFE
Str: ps_icmp6_nd.c
Fmt: Can't find the ND control block
00000000 00000000 00000000 00000000
Task: DS

Not sure where to proceed from here...


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