Buildroot toolchain with c++

I've been playing a bit with building a Nios2 toolchain with c++ support from buildroot svn, and finally I have something that seems to be working. In case someone else are interested; here is a HOWTO:

1) To get global constructors/destructors to work, the latest uClibc snapshot (as of today) is needed. CTOR/DTOR-support must be enabled in the config.

2) UClibc provides its own crti.o/crtn.o-files, so gcc's internal ones has to be disabled. The start/end-files (ctri/crtbegin.o, crtn/ctrend.o) must always be linked in when uClibc CTOR/DTOR-support is enabled, to get rid of unresolved symbol errors. The gcc-patch below fixes these issues:

diff -urN gcc-3.4.6.orig/gcc/config/nios2/nios2.h gcc-3.4.6/gcc/config/nios2/nios2.h

--- gcc-3.4.6.orig/gcc/config/nios2/nios2.h 2007-01-04 09:40:02.000000000 +0100

+++ gcc-3.4.6/gcc/config/nios2/nios2.h 2007-01-04 09:49:16.000000000 +0100

@@ -88,8 +88,6 @@

N_("All ld/st instructins do not use io variants (default)") },

{ "smallc", 0,

N_("Link with a limited version of the C library") },

- { "ctors-in-init", 0,

- "" /* undocumented: N_("Link with static constructors and destructors in init") */ },

{ "", TARGET_DEFAULT, 0 }

}

@@ -140,12 +138,12 @@

# define STARTFILE_SPEC

"%{msys-crt0=*: %*} %{!msys-crt0=*: crt1%O%s}

%{msys-crt0=: %eYou need a C startup file for -msys-crt0=}

- %{mctors-in-init: crti%O%s crtbegin%O%s}

+ crti%O%s crtbegin%O%s

"

# undef ENDFILE_SPEC

# define ENDFILE_SPEC

- "%{mctors-in-init: crtend%O%s crtn%O%s}"

+ " crtend%O%s crtn%O%s"

/***********************

diff -urN gcc-3.4.6.orig/gcc/config/nios2/t-nios2 gcc-3.4.6/gcc/config/nios2/t-nios2

--- gcc-3.4.6.orig/gcc/config/nios2/t-nios2 2007-01-04 09:40:02.000000000 +0100

+++ gcc-3.4.6/gcc/config/nios2/t-nios2 2007-01-04 09:47:25.000000000 +0100

@@ -36,17 +36,7 @@

echo '' > ${DPBIT}

cat $(srcdir)/config/fp-bit.c >> ${DPBIT}

-EXTRA_MULTILIB_PARTS = crtbegin.o crtend.o crti.o crtn.o

-

-# Assemble startup files.

-$(T)crti.o: $(srcdir)/config/nios2/crti.asm $(GCC_PASSES)

- $(GCC_FOR_TARGET) $(GCC_CFLAGS) $(MULTILIB_CFLAGS) $(INCLUDES)

- -c -o $(T)crti.o -x assembler-with-cpp $(srcdir)/config/nios2/crti.asm

-

-$(T)crtn.o: $(srcdir)/config/nios2/crtn.asm $(GCC_PASSES)

- $(GCC_FOR_TARGET) $(GCC_CFLAGS) $(MULTILIB_CFLAGS) $(INCLUDES)

- -c -o $(T)crtn.o -x assembler-with-cpp $(srcdir)/config/nios2/crtn.asm

-

+EXTRA_MULTILIB_PARTS = crtbegin.o crtend.o

# # You may need to provide additional# defines at the beginning of

# # fp-bit.c and dp-bit.c to control target endianness and other options

3) To fix gcc configuration, the buildroot gcc-patch from http://nioswiki.jot.com/wikihome/operating.../buildrootguide (http://nioswiki.jot.com/wikihome/operatingsystems/buildrootguide) must be added:

Index: toolchain/gcc/3.4.6/100-uclibc-conf.patch

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

--- toolchain/gcc/3.4.6/100-uclibc-conf.patch (revision 14569)

+++ toolchain/gcc/3.4.6/100-uclibc-conf.patch (working copy)

@@ -1,11 +1,3 @@

---- gcc-3.4.1/gcc/config/t-linux-uclibc

-+++ gcc-3.4.1/gcc/config/t-linux-uclibc

-@@ -0,0 +1,5 @@

-+# Remove glibc specific files added in t-linux

-+SHLIB_MAPFILES := $(filter-out $(srcdir)/config/libgcc-glibc.ver, $(SHLIB_MAPFILES))

-+

-+# Use unwind-dw2-fde instead of unwind-dw2-fde-glibc

-+LIB2ADDEH := $(subst unwind-dw2-fde-glibc.c,unwind-dw2-fde.c,$(LIB2ADDEH))

--- gcc-3.4.1/gcc/config.gcc

+++ gcc-3.4.1/gcc/config.gcc

@@ -2310,10 +2310,16 @@

@@ -18,7 +10,7 @@

+# Rather than hook into each target, just do it after all the linux

+# targets have been processed

+case ${target} in

-+*-linux-uclibc*) tm_defines="${tm_defines} USE_UCLIBC" ; tmake_file="${tmake_file} t-linux-uclibc"

++*-linux-uclibc*) tm_defines="${tm_defines} USE_UCLIBC"

+esac

# Support for --with-cpu and related options (and a few unrelated options,

4) To get rid of stdlibc++ compilation errors, this patch must be added:

http://gcc.gnu.org/bugzilla/attachment.cgi?id=6132 (http://gcc.gnu.org/bugzilla/attachment.cgi?id=6132)

and in addition the uClibc locale-patch (toolchain/gcc/3.4.6/200-uclibc-locale.patch) must be disabled.

5) Elf2flt fixes:

Rather than using the elf2flt linker-script from http://nioswiki.jot.com/wikihome/operating.../buildrootguide (http://nioswiki.jot.com/wikihome/operatingsystems/buildrootguide) I have used the one in buildroot with an updated elf2flt.nios2.conditional patch posted in http://bugs.uclibc.org/view.php?id=618 (http://bugs.uclibc.org/view.php?id=618). Link to patch:

http://bugs.uclibc.org/file_download.php?f...id=601&type=bug (http://bugs.uclibc.org/file_download.php?file_id=601&type=bug)

This seems to work just fine.

6) And last, a small patch for binutils to fix compilation errors with gcc 4.x.x:

--- binutils/gas/config/tc-nios2.c.orig 2006-03-13 03:39:58.000000000 +0100

+++ binutils/gas/config/tc-nios2.c 2006-11-09 15:31:46.000000000 +0100

@@ -1837,7 +1837,7 @@

/* apply the rightshift */

- (signed) fixup >>= howto->rightshift;

+ fixup >>= howto->rightshift;

/* truncate the fixup to right size */

switch (fixP->fx_r_type)

@@ -1882,7 +1882,7 @@

nios2_check_overflow (valueT fixup, reloc_howto_type * howto)

{

/* apply the rightshift before checking for overflow */

- (signed) fixup >>= howto->rightshift;

+ fixup >>= howto->rightshift;

/* check for overflow - return TRUE if overflow, FALSE if not */

switch (howto->complain_on_overflow)

- Atle