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Date:	Thu, 14 Mar 2013 15:37:30 +0800
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Subject:	gdb bt gives many question marks
From:	Ken Huang <csuhgw AT gmail DOT com>
To:	cygwin AT cygwin DOT com
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Hi all,

I have a problem when using gdb to debug my program in cygwin, the 'bt' command
gives me many '??'.

So I write a quite easy program named abort.c which just aborts. after
compiled with
"gcc -g abort.c -o abort" and run with " gdb abort", it aborts as
expected. At this time
I type "bt" in gdb to see the backtrace info, but it only gives the following:
(gdb) bt
#0  0x7c92e514 in ntdll!LdrAccessResource () from
/cygdrive/c/WINDOWS/system32/ntdll.dll
#1  0x7c92df5a in ntdll!ZwWaitForSingleObject () from
/cygdrive/c/WINDOWS/system32/ntdll.dll
#2  0x7c8025db in WaitForSingleObjectEx () from
/cygdrive/c/WINDOWS/system32/kernel32.dll
#3  0x00000714 in ?? ()
#4  0x00000000 in ?? ()
(gdb) bt full
#0  0x7c92e514 in ntdll!LdrAccessResource () from
/cygdrive/c/WINDOWS/system32/ntdll.dll
No symbol table info available.
#1  0x7c92df5a in ntdll!ZwWaitForSingleObject () from
/cygdrive/c/WINDOWS/system32/ntdll.dll
No symbol table info available.
#2  0x7c8025db in WaitForSingleObjectEx () from
/cygdrive/c/WINDOWS/system32/kernel32.dll
No symbol table info available.
#3  0x00000714 in ?? ()
No symbol table info available.
#4  0x00000000 in ?? ()
No symbol table info available.

My test program is as follows:
void bar()
{
    abort();
}

void foo()
{
    bar();
}

int main()
{
    foo();
}

So, did I compile wrong, or is there something I didn't set properly?

Thanks,
Ken

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