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From:	Jim Marshall <jim DOT marshall AT wbemsolutions DOT com>
Subject:	Re: Issue with GDB under Cygwin and XP
Date:	Tue, 12 Feb 2008 23:09:51 -0500
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Ray Hurst wrote:
> I'm running under Windows XP and Cygwin.
> 
> I ran GDB on a simple C program and captured the output (below).
> I have a few questions:
> 
> Why can I run the program several times with no errors but as soon as I 
> set a breakpoint at main it gets a SIGSEGV fault?
> 
> Why does the backtrace show only addresses?
> 
> 
> C:\Documents and Settings\Ray 
> Hurst\workspace\CDT\HelloWorld-ANSIC\Debug>gdb Hel
> loWorld-ANSIC.exe
> GNU gdb 6.5.50.20060706-cvs (cygwin-special)
> Copyright (C) 2006 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and you 
> are
> welcome to change it and/or distribute copies of it under certain 
> conditions.
> Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB.  Type "show warranty" for details.
> This GDB was configured as "i686-pc-cygwin"...
> (gdb) list
> 5        Version     :
> 6        Copyright   : Your copyright notice
> 7        Description : Hello World in C, Ansi-style
> 8 =======================================================================
> =====
> 9        */
> 10
> 11      #include <stdio.h>
> 12      #include <stdlib.h>
> 13
> 14      int main(void) {
> (gdb) list 20
> 15              puts("!!!Hello World!!!"); /* prints !!!Hello World!!! */
> 16              return EXIT_SUCCESS;
> 17      }
> (gdb) run
> Starting program: /cygdrive/c/Documents and Settings/Ray 
> Hurst/workspace/CDT/Hel
> loWorld-ANSIC/Debug/HelloWorld-ANSIC.exe
> Loaded symbols for /cygdrive/c/WINDOWS/system32/ntdll.dll
> Loaded symbols for /cygdrive/c/WINDOWS/system32/kernel32.dll
> Loaded symbols for /cygdrive/c/WINDOWS/system32/cygwin1.dll
> Loaded symbols for /cygdrive/c/WINDOWS/system32/advapi32.dll
> Loaded symbols for /cygdrive/c/WINDOWS/system32/rpcrt4.dll
> Loaded symbols for /cygdrive/c/WINDOWS/system32/secur32.dll
> !!!Hello World!!!
> 
> Program exited normally.
> (gdb) run
> Starting program: /cygdrive/c/Documents and Settings/Ray 
> Hurst/workspace/CDT/Hel
> loWorld-ANSIC/Debug/HelloWorld-ANSIC.exe
> Loaded symbols for /cygdrive/c/WINDOWS/system32/ntdll.dll
> Loaded symbols for /cygdrive/c/WINDOWS/system32/kernel32.dll
> Loaded symbols for /cygdrive/c/WINDOWS/system32/cygwin1.dll
> Loaded symbols for /cygdrive/c/WINDOWS/system32/advapi32.dll
> Loaded symbols for /cygdrive/c/WINDOWS/system32/rpcrt4.dll
> Loaded symbols for /cygdrive/c/WINDOWS/system32/secur32.dll
> !!!Hello World!!!
> 
> Program exited normally.
> (gdb) b main
> Breakpoint 1 at 0x401050: file ../src/HelloWorld-ANSIC.c, line 14.
> (gdb) run
> Starting program: /cygdrive/c/Documents and Settings/Ray 
> Hurst/workspace/CDT/Hel
> loWorld-ANSIC/Debug/HelloWorld-ANSIC.exe
> Loaded symbols for /cygdrive/c/WINDOWS/system32/ntdll.dll
> Loaded symbols for /cygdrive/c/WINDOWS/system32/kernel32.dll
> Loaded symbols for /cygdrive/c/WINDOWS/system32/cygwin1.dll
> Loaded symbols for /cygdrive/c/WINDOWS/system32/advapi32.dll
> Loaded symbols for /cygdrive/c/WINDOWS/system32/rpcrt4.dll
> Loaded symbols for /cygdrive/c/WINDOWS/system32/secur32.dll
> 
> Program received signal SIGSEGV, Segmentation fault.
> [Switching to thread 4896.0x1314]
> 0x000007f4 in ?? ()
> (gdb) bt
> #0  0x000007f4 in ?? ()
> #1  0x00000000 in ?? ()
> (gdb)
> 
> Ray
> 
> 
Works fine on my Windows XP Pro machine using the same GDB and gcc 
version 3.4.4. What gcc version do you have?

The stack trace would indicate that the crash is occurring before it 
gets to your main function, since that code doesn't have debug symbols 
you get addresses.


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