NetNews Usenet Archive 1992 #18/NN_1992_18.iso/spool/comp/unix/aix/8812

Text File | 1992-08-14 | 2.7 KB | 60 lines

Newsgroups: comp.unix.aix
Path: sparky!uunet!newsgate.watson.ibm.com!yktnews!admin!watson!xanadu.btv.ibm.com!lpickup
From: [e-mail] (Lance Pickup)
Subject: Re: Debuging Segmentation Violation Fault
Sender: @watson.ibm.com
Message-ID: <[e-mail]>
Date: Fri, 14 Aug 92 12:16:19 GMT
Reply-To: [e-mail]
References:  <[e-mail]>
Organization: IBM Technology Products
Keywords: Segmentation Violation
Lines: 46

In article <[e-mail]>, [e-mail] (Jing Huang) writes:
|>      Dear netters, I have always wanted to ask this question. To me, the
|> most horrifying error a program can have is "segmentation violation". I never
|> have any clear idea about how to debug this kind of fault. Can someone give
|> me some advice from his own experience on how to solve this fault?
|>
|>      I have this HUGE C program (20,000 lines). Everything worked fine
|> until the other day I added a few (about 10) lines to it. Then all of a sudden,
|> it keeps giving me this "segmentation violation". I ran "dbx" to see if I can
|> get some clue, it gave me something like:
|>
|> segmentation violation in malloc_y at 0xd00d43f0
|> 0xd00d43f0 (malloc_y+0x2a8) 7c7c45aa       stsi   r3,r28,0x8
|>
|>      From these two lines, all I can guess is that the fault is related to
|> "malloc". But "malloc" is used more than dozens of times throughout the
|> program, how am I supposed to know "who steps on whose toe and where".
|>
|>      I am desperate. Could someone tell me what other things I should do
|> beyond these two lines? Or maybe what books or manuals should I read to get
|> more information? What do those address-like (?) numbers all mean?
...

Jing,

  The next step inside dbx would be to use the t command to get a
list of the traceback stack.  The line you see above will be at the
top, the function which called it will be on the next line, and so
on.  You will eventually see your functions in the traceback,
and if you compiled with -g you can even see line numbers and
parameters passed.  This should point you to the line in your code
which is calling malloc which fails.

  Usually malloc fails when it can't honor your request for storage.
i.e. you've requested a huge amount of memory (or even worse, a
negative amount--which I believe translates into a huge amount as
well!).
--
    ...Lance

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