NNTP-Posting-Date:	Mon, 11 Nov 2002 06:54:23 -0600
From:	Charles Wilkins <chas AT pcscs DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: i686-pc-msdosdjgpp-g++ problems (long)
Date:	Mon, 11 Nov 2002 07:56:20 -0500
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>No, no, no, this is wrong.  You should set the breakpoint _before_ 
>running the program, not after.  That is, type "br *0x0001e1df" right 
>after GDB prints its startup blurb, and _then_ type "run".

Ok, here are the results doing it this way.
C:\Archives\RIP2\DJGPP\bin>gdb wel-g
GNU gdb 5.2.1
Copyright 2002 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 "i386-pc-msdosdjgpp"...
(gdb) br *0x0001e1df
Breakpoint 1 at 0x1e1df
(gdb) run
Starting program: c:/Archives/RIP2/DJGPP/bin/wel-g.exe

Breakpoint 1, 0x0001e1df in
std::ostream::sentry::sentry(std::ostream&) ()
(gdb) disass 0x0001e1df
Dump of assembler code for function _ZNSo6sentryC1ERSo:
0x1e1d0 <_ZNSo6sentryC1ERSo>:        push   %ebp
0x1e1d1 <_ZNSo6sentryC1ERSo+1>:        mov    %esp,%ebp
0x1e1d3 <_ZNSo6sentryC1ERSo+3>:        push   %ebx
0x1e1d4 <_ZNSo6sentryC1ERSo+4>:        mov    0xc(%ebp),%ecx
0x1e1d7 <_ZNSo6sentryC1ERSo+7>:        mov    0x8(%ebp),%edx
0x1e1da <_ZNSo6sentryC1ERSo+10>:        mov    (%ecx),%eax
0x1e1dc <_ZNSo6sentryC1ERSo+12>:        mov    %ecx,0x4(%edx)
0x1e1df <_ZNSo6sentryC1ERSo+15>:        mov    0xfffffff4(%eax),%ebx
0x1e1e2 <_ZNSo6sentryC1ERSo+18>:        lea    (%ebx,%ecx,1),%eax
0x1e1e5 <_ZNSo6sentryC1ERSo+21>:        mov    0x14(%eax),%ebx
0x1e1e8 <_ZNSo6sentryC1ERSo+24>:        test   %ebx,%ebx
0x1e1ea <_ZNSo6sentryC1ERSo+26>:        sete   %al
0x1e1ed <_ZNSo6sentryC1ERSo+29>:        movzbl %al,%eax
0x1e1f0 <_ZNSo6sentryC1ERSo+32>:        test   %al,%al
0x1e1f2 <_ZNSo6sentryC1ERSo+34>:        mov    %al,(%edx)
0x1e1f4 <_ZNSo6sentryC1ERSo+36>:        je     0x1e210
<_ZNSo6sentryC1ERSo+64>
0x1e1f6 <_ZNSo6sentryC1ERSo+38>:        mov    (%ecx),%eax
0x1e1f8 <_ZNSo6sentryC1ERSo+40>:        mov    0xfffffff4(%eax),%edx
0x1e1fb <_ZNSo6sentryC1ERSo+43>:        add    %edx,%ecx
0x1e1fd <_ZNSo6sentryC1ERSo+45>:        mov    0x70(%ecx),%eax
0x1e200 <_ZNSo6sentryC1ERSo+48>:        test   %eax,%eax
0x1e202 <_ZNSo6sentryC1ERSo+50>:        je     0x1e210
<_ZNSo6sentryC1ERSo+64>
0x1e204 <_ZNSo6sentryC1ERSo+52>:        mov    %eax,0x8(%ebp)
---Type <return> to continue, or q <return> to quit---
0x1e207 <_ZNSo6sentryC1ERSo+55>:        pop    %ebx
0x1e208 <_ZNSo6sentryC1ERSo+56>:        pop    %ebp
0x1e209 <_ZNSo6sentryC1ERSo+57>:        jmp    0x1dde0 <_ZNSo5flushEv>
0x1e20e <_ZNSo6sentryC1ERSo+62>:        mov    %esi,%esi
0x1e210 <_ZNSo6sentryC1ERSo+64>:        pop    %ebx
0x1e211 <_ZNSo6sentryC1ERSo+65>:        pop    %ebp
0x1e212 <_ZNSo6sentryC1ERSo+66>:        ret
0x1e213 <_ZNSo6sentryC1ERSo+67>:        nop
0x1e214 <_ZNSo6sentryC1ERSo+68>:        nop
0x1e215 <_ZNSo6sentryC1ERSo+69>:        nop
0x1e216 <_ZNSo6sentryC1ERSo+70>:        nop
0x1e217 <_ZNSo6sentryC1ERSo+71>:        nop
0x1e218 <_ZNSo6sentryC1ERSo+72>:        nop
0x1e219 <_ZNSo6sentryC1ERSo+73>:        nop
0x1e21a <_ZNSo6sentryC1ERSo+74>:        nop
0x1e21b <_ZNSo6sentryC1ERSo+75>:        nop
0x1e21c <_ZNSo6sentryC1ERSo+76>:        nop
0x1e21d <_ZNSo6sentryC1ERSo+77>:        nop
0x1e21e <_ZNSo6sentryC1ERSo+78>:        nop
0x1e21f <_ZNSo6sentryC1ERSo+79>:        nop
End of assembler dump.
(gdb) n
Single stepping until exit from function _ZNSo6sentryC1ERSo,
which has no line number information.

Program received signal SIGSEGV, Segmentation fault.
0x0001e1df in std::ostream::sentry::sentry(std::ostream&) ()
(gdb) n
Single stepping until exit from function _ZNSo6sentryC1ERSo,
which has no line number information.
Exiting due to signal SIGSEGV
General Protection Fault at eip=0001e1df
eax=00000000 ebx=00043b58 ecx=00043b58 edx=000c7f60 esi=00000054
edi=00001630
ebp=000c7f28 esp=000c7f24 program=c:\Archives\RIP2\DJGPP\bin\wel-g.exe
cs: sel=01ef  base=022c0000  limit=000cffff
ds: sel=01f7  base=022c0000  limit=000cffff
es: sel=01f7  base=022c0000  limit=000cffff
fs: sel=01e7  base=00009e10  limit=00003fff
gs: sel=0207  base=00000000  limit=0010ffff
ss: sel=01f7  base=022c0000  limit=000cffff
App stack: [000c7fdc..00047fdc]  Exceptn stack: [00047e8c..00045f4c]

Call frame traceback EIPs:
  0x0001e1df
  0x0001e44e
  0x0000167e
  0x0000d817

Program exited with code 0377.
(gdb)

>
>> Could this problem be resulting from the libstdc++.a archive library
>> having a name that defies DOS naming conventions?
>
>No, but is it possible that libstdc++.a you linked against was compiled 
>for native GNU/Linux compiler, not as a cross-compiled library for DJGPP?
No.  

Note: that I am using gcc and libstdc++ from this package:
bef1ba664e820ee634b55b3f77fcebf3  gcc-3.2.tar.gz

Here is the exact command I configured gcc-3.2 and libstdc++-v3 with.

cd ~/gcc-3.2-obj
../gcc-3.2-src/configure
--target=i686-pc-msdosdjgpp
--prefix=/usr/local/compiler/cross2/djgpp
--without-newlib
--with-headers=/usr/local/compiler/cross2/djgpp/i686-pc-msdosdjgpp/include
--with-libs=/usr/local/compiler/cross2/djgpp/lib
/usr/local/compiler/cross2/djgpp/i686-pc-msdosdjgpp/lib

I have also tried just doing:
../gcc-3.2-src/configure
--target=i686-pc-msdosdjgpp
--prefix=/usr/local/compiler/cross2/djgpp
--with-headers=/usr/local/compiler/cross2/djgpp/i686-pc-msdosdjgpp/include

Both above configurations have the same effect WRT the sigsegv.

I am able to simply link against against libstdc++.a without getting
the SIGSEGV.  It is only when I include a libstdc++ header such as
<iostream> that I get the SIGSEGV.

====================================================
When I compile this porgram:
#include <stdio.h>

int main()
{
	printf("Welcome to GNU C++ for Linux programming!\n");
	return 0;
}

like this: (using gcc)
/usr/local/compiler/cross2/djgpp/bin/i686-pc-msdosdjgpp-gcc -lstdc++
-lm welcome.c -o welcome.exe

no sigsegv..  welcome.exe runs in DOS and Win32.

====================================================
When I compile the above program like this: (using g++)
/usr/local/compiler/cross2/djgpp/bin/i686-pc-msdosdjgpp-g++ -lstdc++
-lm welcome.c -o welcome.exe

no sigsegv..  welcome.exe runs in DOS and Win32.

====================================================
but when I compile _this_ program that includes the iostream header, I
have the problem..

#include <iostream>

int main() {
    std::cout << "Welcome to GNU C++ for Linux programming!" <<
std::endl;
    return 0;
}

/usr/local/compiler/cross2/djgpp/bin/i686-pc-msdosdjgpp-g++ -lstdc++
-lm welcome.cpp -o welcome.exe

yes sigsegv..  welcome.exe does not run in DOS and Win32.

====================================================

Note:  when I compile with the header, <cstdio>, I do not get the
sigsegv.

#include <cstdio>

int main()
{
	printf("Welcome to GNU C++ for Linux programming!\n");
	return 0;
}

/usr/local/compiler/cross2/djgpp/bin/i686-pc-msdosdjgpp-g++ -lstdc++
-lm welcome.c -o welcome.exe

no sigsegv..  welcome.exe runs in DOS and Win32.

====================================================

Does this answer your questions?
Please tell me if it would be helpful to provide more information.

Thank you,
Charles

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