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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>
Cc:        freebsd-current@freebsd.org
Subject:   Re: Fatal trap 12: page fault while in kernel mode
Message-ID:  <84dead720812050840j28c95014wf76095c3d6def985@mail.gmail.com>
In-Reply-To: <87zljb8nw6.fsf@roddy.4407.kankyo-u.ac.jp>
References:  <87zljb8nw6.fsf@roddy.4407.kankyo-u.ac.jp>

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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



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