Re: Undetected duplicate symbols

[Khem Raj <khem at mvista dot com>]

Khem Raj wrote:
> Marius Groeger said the following on 02/08/2006 01:49 AM:
> > On Tue, 7 Feb 2006, Khem Raj wrote:
> >
> > > Do you have your own linker script file ? or do you use default one. 
> > > I think you need to have your own for the system
> > > either way you can remove the symbol for linker script and see if 
> > > that works. Would be nice if you could make a short example to 
> > > exhibit the problem.
> >
> > Sure, see below.
> >
> > Writing this example I found the issue not only happens with my MIPS
> > toolchain, but also with my host gcc. Most convincing is the 
> > disassembly; it
> > clearly shows that the _start which I defined as entry point is has been
> > lost. Maybe it's a "feature" that linker script variables override
> > application variables, but don't think I like this feature then...
> >
> > sh# gcc -c -o duplicate.o duplicate.c
> > sh# ld -o duplicate -T duplicate-ld duplicate.o
> > sh# nm duplicate
> > 00000000 T dummy
> > 00000000 T _start
> > mag@mag:~/work> nm duplicate.o
> > 00000000 T dummy
> > 00000025 T _start
> > mag@mag:~/work> objdump -d duplicate
> >
> > duplicate: file format elf32-i386
> >
> > Disassembly of section .text:
> >
> > 00000000 <_start>:
> > 0: 55 push %ebp
> > 1: 89 e5 mov %esp,%ebp
> > 3: 83 ec 04 sub $0x4,%esp
> > 6: c7 45 fc 00 00 00 00 movl $0x0,0xfffffffc(%ebp)
> > d: 8b 45 fc mov 0xfffffffc(%ebp),%eax
> > 10: 83 f8 63 cmp $0x63,%eax
> > 13: 7e 02 jle 17 <_start+0x17>
> > 15: eb 09 jmp 20 <_start+0x20>
> > 17: 8b 45 fc mov 0xfffffffc(%ebp),%eax
> > 1a: 40 inc %eax
> > 1b: 89 45 fc mov %eax,0xfffffffc(%ebp)
> > 1e: eb ed jmp d <_start+0xd>
> > 20: 8b 45 fc mov 0xfffffffc(%ebp),%eax
> > 23: c9 leave
> > 24: c3 ret
> > 25: 55 push %ebp
> > 26: 89 e5 mov %esp,%ebp
> > 28: 83 ec 08 sub $0x8,%esp
> > 2b: c7 45 fc 00 00 0c bf movl $0xbf0c0000,0xfffffffc(%ebp)
> > 32: e8 c9 ff ff ff call 0 <_start>
> > 37: 89 c2 mov %eax,%edx
> > 39: 8b 45 fc mov 0xfffffffc(%ebp),%eax
> > 3c: 89 10 mov %edx,(%eax)
> > 3e: c9 leave
> > 3f: c3 ret
> >
> >
> >
> > Sampel application "duplicate.c":
> > extern int dummy(void)
> > {
> > volatile int i;
> >
> > /* create some .text data to move _start away from the beginning */
> >
> > for(i = 0; i < 100; i++)
> > ;
> >
> > return i;
> > }
> >
> > extern void _start(void)
> > {
> > volatile int *p = (volatile int*)0xbf0c0000;
> >
> > *p = dummy();
> > }
> >
> > Linker script "duplicate-ld":
> > SECTIONS
> > {
> > .text 0x00000000:
> > {
> > _start = . ;
> > *(.text)
> > }
> > }
> >
> > Marius
> This is a bug in ld I think. I filed one in binutils bugzilla #2300
There is a patch already out there.
you can apply to your binutils and see if it works.
http://sourceware.org/ml/binutils/2006-02/msg00126.html
Thanks for reporting.
> ------
> Want more information?  See the CrossGCC FAQ, 
> http://www.objsw.com/CrossGCC/
> Want to unsubscribe? Send a note to crossgcc-unsubscribe@sourceware.org


------
Want more information?  See the CrossGCC FAQ, http://www.objsw.com/CrossGCC/
Want to unsubscribe? Send a note to crossgcc-unsubscribe@sourceware.org