Bus error, help!

Bus error, help!

Post by Andrew Ted Duchows » Thu, 28 Feb 1991 05:01:29


Could someone help me with the following problem:

In the following function, the line delimitted by
/* problem line */ gives me:

  Bus error [malloc:445, 0x....]

but *only* on the first call from a paritular function.
Let's call that function ftn1.  To sate the symptoms
clearly, the program dumps when I click first on a button
that executes ftn1 which calls create_value.  If however,
I click on a different button such that ftn2 calls create_value
first, and then I click a button so that ftn1 calls create_value, no
dump.  Only when I click on the button so that ftn1 calls
create_value first do I get the dump.

I've checked args, and they look ok, so I don't think that's
the faulty parameter.  Can anyone give me any clues why
create_value dumps where and when it does?  I've been looking
at this for about a week, read the DEC manuals for both relevant
Dwt (DEC widgets) and XUI Toolkit widgets, and create_value
appears fine, straight out of the textbook.  What am I doing wrong?

I'm on a DECstation3100 running Ultrix 4.1.  


Widget create_value(parent,str)
Widget parent;
char *str;
  int i=0;
  Arg args[4];
  Widget box,value;

  box = DwtDialogBoxCreate(parent,"textbox",args,1);

  XtSetArg(args[i],DwtNinsertionPointVisible,False); i++;
  XtSetArg(args[i],DwtNborderWidth,0); i++;
  XtSetArg(args[i],DwtNhalfBorder,False); i++;
  XtSetArg(args[i],DwtNvalue,str); i++;

/* problem line */
  value = DwtSTextCreate(box,"textvalue",args,i);
/* problem line */

  return value;



-------------- Not an Official Texas A&M University Document --------------


1. Bus Errors in 1134a


      Okay, rather simple question.  When I hit control halt/sys on
my PDP The SR DISP light goes out, the buss error light comes on, and
the address data panel stays on.  I did the system tests the book sug-
gests.  IE, pulling out the M9302 card at the end of the unibus.  Anyways,
The results of the tests tell me that I have a BUS Grant problem.  What
I need to know is how to fix that.  Where is the bus grant generated and
what would cause it to malfunction?  I have all the cards for 2 complete
PDP-1134A systems so it is mostly a matter of finding out which cards are
good and which aren't and the same with the backplanes.  I should have
enough parts to get one PDP running if I'm lucky.  Thanks in Advance.


---------------------------Three Laws of Programming---------------------------

1.  Any given program, when running, is obsolete.

2.  When putting it into memory remember where you put it.

3.  A computer program does what you tell it to do, not what you want it to do.


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