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Date: Fri, 5 Dec 2008 22:10:10 +0530
From: "Joseph Koshy" <joseph.koshy@gmail.com>
To: "NAKAJI Hiroyuki" <nakaji@jp.freebsd.org>
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Cc: freebsd-current@freebsd.org
Subject: Re: Fatal trap 12: page fault while in kernel mode
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> Fatal trap 12: page fault while in kernel mode
> cpuid = 0; apic id = 00
> fault virtual address   = 0x0
> fault code              = supervisor read, page not present
> instruction pointer     = 0x20:0xc0a57285

> Why this occurs and what do I have to check?

The trap is being caused by a null pointer access.

You may want to take a full dump and use kgdb(1) to investigate the matter:

  ddb> call doadump
  ddb> reset

and after the reboot finishes,

  # kgdb /boot/kernel/kernel /var/crash/vmcore.N

where "vmcore.N" is the name of the dump file saved by savecore(8).

Koshy