How GDB handle this case while program works well in GDB but crash in mormal mode

How GDB handle this case while program works well in GDB but crash in mormal mode

[Renzhong Xiao]

Hi,
    I have some trouble in using GDB 6.3.50_2004-12-28-cvs in Cygwin
to debug the mencoder (which is a program in MPlayer).When I run
mencoder in normal mode,it will pop up an error message saying
mencoder.exe has error and will be closed. But I run mencoder in
gdb,it works well.
    I don't know how to find this bug in GDB,Does GDB has the some
feature to handle this case?

    Any information will be very appreciate!

Renzhong Xiao

Re: How GDB handle this case while program works well in GDB but crash in mormal mode

[Bob Rossi]

On Sun, Jun 05, 2005 at 10:56:43PM +0800, Renzhong Xiao wrote:
> Hi,
>     I have some trouble in using GDB 6.3.50_2004-12-28-cvs in Cygwin
> to debug the mencoder (which is a program in MPlayer).When I run
> mencoder in normal mode,it will pop up an error message saying
> mencoder.exe has error and will be closed. But I run mencoder in
> gdb,it works well.
>     I don't know how to find this bug in GDB,Does GDB has the some
> feature to handle this case?
> 
>     Any information will be very appreciate!

I'm not an expert but there are probably many issues that could make this
appear. For instance, if timing is important, your program might run a
little slower in GDB than normally. If this is the case, things could
potentially run different in your program. Also, if there are memory
runtime error's in MPlayer, your program could act different when run in
different environments.

I would suggest using valgrind in Linux on MPlayer to see if there are
any memory runtime errors.

Bob Rossi

Re: How GDB handle this case while program works well in GDB but crash in mormal mode

[Renzhong Xiao]

Thanks for your timely response, I will download valgrind and have a try.

Renzhong Xiao

On 6/6/05, Bob Rossi <bob@brasko.net> wrote:
> On Sun, Jun 05, 2005 at 10:56:43PM +0800, Renzhong Xiao wrote:
> > Hi,
> >     I have some trouble in using GDB 6.3.50_2004-12-28-cvs in Cygwin
> > to debug the mencoder (which is a program in MPlayer).When I run
> > mencoder in normal mode,it will pop up an error message saying
> > mencoder.exe has error and will be closed. But I run mencoder in
> > gdb,it works well.
> >     I don't know how to find this bug in GDB,Does GDB has the some
> > feature to handle this case?
> >
> >     Any information will be very appreciate!
> 
> I'm not an expert but there are probably many issues that could make this
> appear. For instance, if timing is important, your program might run a
> little slower in GDB than normally. If this is the case, things could
> potentially run different in your program. Also, if there are memory
> runtime error's in MPlayer, your program could act different when run in
> different environments.
> 
> I would suggest using valgrind in Linux on MPlayer to see if there are
> any memory runtime errors.
> 
> Bob Rossi
>

RE: How GDB handle this case while program works well in GDB but crash in mormal mode

[Dave Korn]

----Original Message----
>From: Renzhong Xiao
>Sent: 05 June 2005 15:57

> Hi,
>     I have some trouble in using GDB 6.3.50_2004-12-28-cvs in Cygwin
> to debug the mencoder (which is a program in MPlayer).When I run
> mencoder in normal mode,it will pop up an error message saying
> mencoder.exe has error and will be closed. But I run mencoder in
> gdb,it works well.
>     I don't know how to find this bug in GDB,Does GDB has the some
> feature to handle this case?
> 
>     Any information will be very appreciate!
> 
> Renzhong Xiao


  Perhaps you can use the cygwin just-in-time debugging ability to solve the
problem; that way the program will run as usual, without the debugger
attached, up to the point when the error occurs; then cygwin will attach the
debugger once the error has happened.  Hopefully that means the initial
stages of running the program will be undisturbed and the error will not be
masked.

  To make this work, add 'error_start=C:\cygwin\bin\gdb.exe' (or whatever
else is the win32 path to gdb.exe, according to where you installed cygwin)
to your $CYGWIN environment variable before you start a cygwin shell, then
run mencoder.  Hopefully as soon as it crashes cygwin will attach teh
debugger for you.


    cheers,
      DaveK
-- 
Can't think of a witty .sigline today....