[uClinux-dev] Does ucfront work with libstdc++.a?

[Erwin Authried]

Hello Wolfgang,
for now, I have built a gcc-3.4.6 toolchain only. I have used the
OpenWrt Kamikaze distribution to build the toolchain, made several
modifications for uClinux, and added elf2flt. I have attached my elf2flt
ld script. 

Regards,
Erwin

Am Sonntag, den 21.10.2007, 23:17 +0200 schrieb Wolfgang Mües:
> Erwin,
> 
> On Sonntag, 21. Oktober 2007, Erwin Authried wrote:
> > in elf2flt.ld, the ctor table starts with the nr. of entries in the
> > table "LONG((__CTOR_END__ - __CTOR_LIST__) / 4 - 2)", and ends with
> > 0.
> Yes. 
> 
> > The newer compilers just have the ctor entries, and 0xffffffff as 
> > the end marker (if I remember correctly). The end marker isn't
> > required in the ld script because it comes from the library.
>  
> OK.
> > Because of the elf2flt.ld entries, you will see multiple definitions 
> > of the  __CTOR_LIST__, __DTOR_LIST__ entries. It's possible that this
> > doesn't cause any harm, but it's rather confusing, at least. The main 
> > problem with the 3.4 was the fact that the library for calling the 
> > ctors/dtors is compiled without -msingle-pic-base, causing a crash.
> 
> This is my linker script:
> 
> > 		. = ALIGN(4) ;
> > 		__CTOR_LIST__ = .;
> > 		LONG((__CTOR_END__ - __CTOR_LIST__) / 4 - 2)
> > SINGLE_LINK:	/* gcc uses crtbegin.o to find the start of
> > SINGLE_LINK:	   the constructors, so we make sure it is
> > SINGLE_LINK:	   first.  Because this is a wildcard, it
> > SINGLE_LINK:	   doesn't matter if the user does not
> > SINGLE_LINK:	   actually link against crtbegin.o; the
> > SINGLE_LINK:	   linker won't look for a file to match a
> > SINGLE_LINK:	   wildcard.  The wildcard also means that it
> > SINGLE_LINK:	   doesn't matter which directory crtbegin.o
> > SINGLE_LINK:	   is in.  */
> > SINGLE_LINK:	KEEP (*crtbegin*.o(.ctors))
> > SINGLE_LINK:	/* We don't want to include the .ctor section from
> > SINGLE_LINK:	   from the crtend.o file until after the sorted ctors.
> > SINGLE_LINK:	   The .ctor section from the crtend file contains the
> > SINGLE_LINK:	   end of ctors marker and it must be last */
> > SINGLE_LINK:	KEEP (*(EXCLUDE_FILE (*crtend*.o ) .ctors))
> > SINGLE_LINK:	KEEP (*(SORT(.ctors.*)))
> > 		KEEP (*(.ctors))
> > 		LONG(0)
> > 		__CTOR_END__ = .;
> > 		__DTOR_LIST__ = .;
> > 		LONG((__DTOR_END__ - __DTOR_LIST__) / 4 - 2)
> > SINGLE_LINK:	KEEP (*crtbegin*.o(.dtors))
> > SINGLE_LINK:	KEEP (*(EXCLUDE_FILE (*crtend*.o ) .dtors))
> > SINGLE_LINK:	KEEP (*(SORT(.dtors.*)))
> > 		KEEP (*(.dtors))
> > 		LONG(0)
> > 		__DTOR_END__ = .;
> 
> Can you show me how to modify this for gcc 4.0.x?
> 
> And many thanks for your explanations!
> 
> regards
> Wolfgang
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