Fatal trap 18

Andriy Gapon avg at icyb.net.ua
Fri Nov 5 15:22:55 UTC 2010

on 05/11/2010 16:53 Dan Allen said the following:
> On 3 Nov 2010, at 2:40 AM, Andriy Gapon wrote:
>> 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.
> Okay, I have been researching my UP/SMP problem.
> In the past, before recent "Intel topology" changes, on my Toshiba Satellite U205 machine if I used a kernel with ACPI support, only 1 logical CPU showed up in FreeBSD 8.1-STABLE.  When I booted into Windows XP on the same machine, with the same BIOS settings, I would see 2 logical CPUs.  If I built a FreeBSD kernel WITHOUT ACPI support and left the BIOS settings as they were above, I then would see 2 logical CPUs.
> Now with these recent FreeBSD changes I cannot get the machine to EVER recognize a 2nd logical processor, but if I boot into Windows XP I still see two CPUs, so we still have a bug in this new Intel topology code.

Technically speaking this has nothing to do with topology code.
Topology code decides how detected (logical) CPUs are layed out, whether there are
multiple sockets, or cores, or both, or etc.
Different code is responsible for discovering those multiple processors in the
first place.  And that code can not work without proper assistance from BIOS.

> This laptop has an Intel Core Duo T2400 @ 1.83 GHz chip.  (The BIOS is set to provide multiple logical CPUs in all cases and Andriy, I am using your patched kernel.)
> Is there anything else I can do to help you understand this system config?
> What next?

Let's look at the following:
0. your kernel config
1. verbose dmesg
2. acpidump -dt output
3. x86info -a (sysutils/x86info)

Andriy Gapon

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