*BSD News Article 17065


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From: cgd@erewhon.CS.Berkeley.EDU (Chris G. Demetriou)
Newsgroups: comp.os.386bsd.questions
Subject: FAQ Answer: What does the "trap type nn" message mean?
Date: 12 Jun 93 19:57:52
Organization: Kernel Hackers 'r' Us
Lines: 36
Distribution: world
Message-ID: <CGD.93Jun12195752@erewhon.CS.Berkeley.EDU>
NNTP-Posting-Host: erewhon.cs.berkeley.edu

[ i just wrote this up, because i've seen this asked a lot of times,
  and i've seen almost as many incorrect interpretations of the panic
  message. i'm just about to send it off to Dave Burgess... -- cgd ]

FAQ:    What does the "trap type nn" message mean when the system crashes?

Answer:

That message means that the system received an unexpected (and
unwanted) trap that probably indicates some form of kernel bug.

The number (which appears in place of "nn" above) is *NOT* the i386
or i386 trap type, it is a BSD-defined trap type number.

The definitions of the various trap types can be found in
/usr/include/machine/trap.h.

two of the more common ones are:
        9       T_PROTFLT       protection fault
                                (The kernel tried executing code
                                which was not noted as "executable".
                                This happens if the kernel jumps to
                                a bogus location.)
        12      T_PAGEFLT       page fault
                                (The kernel tried to access a bogus
                                area of memory.  This can happen if
                                an invalid pointer is dereferenced.)



chris
--
Chris G. Demetriou                                    cgd@cs.berkeley.edu

   "386bsd as depth first search: whenever you go to fix something you
       find that 3 more things are actually broken." -- Adam Glass