Re: ARP panic in HEAD

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Mon, Oct 12, 2026 at 06:12:26PM -0400, Greg Troxel wrote:
> Manuel Bouyer <bouyer%antioche.eu.org@localhost> writes:
> 
> >>   - what did you update from?
> >
> > It's a test system so I have 3 partitions: one for netbsd-10, one for
> > netbsd-11 and one for HEAD (which was previously netbsd-9).  The
> > /boot.cfg loader let me choose which one I want.  The hardware has not
> > changed for several years
> 
> I understand that as "I was not running a recent current current".

Yes

> 
> >>   - how many times has it happened
> >
> > I got a first one after maybe an hour of uptime. A second one just
> > after reboot, it didn't reach the login: prompt. A third one occured
> > overnight.  After that I installed a new kernel with the attached
> > diff, it didn't panic yet. One possibility is that it's another
> > instance of over-optimisation from the compiler. Unfortunably I didn't
> > keep the crashing kernel around (but I can revert the patch and
> > rebuild).
> 
> I guess you will wait and see if that diff "fixes" the problem, or if
> it fires and what the op/oop correspondence is.

I did wait until this morning. The system ran for 3 days without issues.
I rebuilt a kernel without the patch, rebooted and got a panic in
less than 1 hour.

I looked at the generated assembly of the stock in_arpinput() (without
the patch). I looked at the x86 assembly for both patched and unpatched
version but d dn't spot anything obvious.

Will try a kernel with only the KASSERT changed to KASSERTMSG
to print op

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--