Fatal trap 18

Andriy Gapon avg at freebsd.org
Wed Nov 3 08:40:33 UTC 2010

on 03/11/2010 10:18 Sergey Kandaurov said the following:
> On 3 November 2010 08:30, Dan Allen <danallen46 at airwired.net> wrote:
>> FreeBSD 8.1-STABLE sometime after 10/28/2010 has caused a fatal boot error on my Toshiba U205, 1.8 GHz Core Duo laptop.
>> Many times every week I sync with STABLE and build everything.  I have been doing this for years.
>> I sync'd (via csup) and built on 10/28/2010 and everything was fine.
>> Then I sync'd yesterday 11/1/2010 and it crashes on boot.  The diagnostics print out the following:
>> ---
>> Fatal trap 18: integer divide fault while in kernel mode
>> kdb_backtrace
>> panic
>> trap_fatal
>> trap
>> calltrap
>> topo_probe
>> cpu_topo
>> smp_topo
>> sched_setup
>> mi_startup
>> ---
>> I reverted at the loader via boot /boot/kernel.old, resync'd today, rebuilt, and things are still broken.

Right, if you never report the problems you get, the chance that they are fixed
is very slim.

> It's possible in theory to leave cpu_logical as zero in topo_probe_0x4().
> So, it makes sense to add some sort of the check.

Actually - not exactly.

This problem seems to happen only on SMP systems that for some reason run as UP.
E.g. because ACPI and/or APIC are disabled.
Or some other BIOS configuration.
But I am not sure what exactly is the case here.
Verbose dmesg from a working kernel would be helpful.

Following the relevant mailing lists sometimes helps to prepare for the future:
Andriy Gapon

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