From owner-freebsd-current  Fri Oct 18 14: 4: 6 2002
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Date: Fri, 18 Oct 2002 14:02:42 -0700
From: Terry Lambert <tlambert2@mindspring.com>
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To: Alexander Leidinger <Alexander@Leidinger.net>
Cc: current@freebsd.org
Subject: Re: page fault while in vm86 mode
References: <20021018121229.1bff0d43.Alexander@Leidinger.net>
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Alexander Leidinger wrote:
> Fatal trap 12: page fault while in vm86 mode
                 ^
                 |
                 a page fault

> #4  0xc0265055 in trap_pfault (frame=0xc0545fa8, usermode=0, eva=803202)
                                 ^                 ^           ^
                                 |                 |           |
                                 |                 |           On a user address
                                 |                 In kernel mode
                                 A trap from kernel code


> This doesn't look much to me. I'm used to see more frames here. What can I do
> do debug this further?

You can load up gdb, and decode all the variables in the trap_pfault()
function, so that we can tell which code path resulted in the problem.

Specifically, we need to know whether:

o	Which map vm->vm_map refers to?
o	Whether vm_fault failed?
o	The value of 'map' and the value of 'kmem_map' and 'kernel_map'?
o	The value of p->p_lock
o	The value of td->td_intr_nesting_level == 0
o	If  PCPU_GET(curpcb) is non-NULL
o	If so, if PCPU_GET(curpcb)->pcb_onfault is non-NULL

Notice that this is the same problem that is currently being discussed
in two other message threads, one on -current, and one on -hackers.

Thanks,
-- Terry

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