Building a GCC toolchain for an i386 target, with soft-float support.

Mian M. Hamayun
Tue Aug 2 12:49:00 GMT 2011

Hello Everyone,

I am trying to build a gcc toolchain with newlib for an i386 target 
which doesn't support hw float instructions. In fact it is a virtual 
machine which I am targeting. So when I compile my applications with 
"-msoft-float" flag, I get quite a few unresolved symbols.

For Example:
Sources/susan.c:979: undefined reference to `__floatsisf'
Sources/susan.c:979: undefined reference to `__divsf3'
Sources/susan.c:1626: undefined reference to `__subdf3'
Sources/susan.c:1628: undefined reference to `__mulsf3'

So my obvious guess is to rebuild the gcc toolchain and/or newlib using 
"--with-float=soft" and/or "--enable-soft-float" options. But so far I 
haven't been able to build a toolchain that solves this issue. In fact 
the toolchain compiles, but I still get the unresolved symbols.

Here is the procedure that I followed:

1) Binutils
   ${TMP_DIR}/${BINUTILS_DIR}/configure  \
   --prefix=${INSTALL_DIR}               \
   --target=${TARGET}                    \
   --disable-nls                         \
   --disable-werror                      \
   --enable-multilib                     \
   --with-float=soft                     \
   --enable-soft-float                   \
     &> logs/configure.log || return

   make install

2) GCC Bootstrap
   ${TMP_DIR}/${GCC_DIR}/configure   \
   --prefix=${INSTALL_DIR}           \
   --target=${TARGET}                \
   --disable-nls                     \
   --enable-multilib                 \
   --with-newlib                     \
   --enable-soft-float               \
   --enable-interwork                \
   --enable-languages=c      &> logs/configure.log || return

   make all-gcc
   make install-gcc

3) Newlib
   ${TMP_DIR}/${NEWLIB_DIR}/configure      \
   --prefix=${INSTALL_DIR}                 \
   --target=${TARGET}                      \
   --disable-nls                           \
   --enable-multilib                       \
   --enable-interwork                      \
   --enable-newlib-io-long-long            \
   --enable-newlib-io-long-double          \
   --enable-newlib-io-c99-formats          \
   --disable-newlib-may-supply-syscalls    \
   --enable-newlib-multithread             \
   --with-float=soft                       \
   --enable-soft-float                     \
   --disable-newlib-supplied-syscalls      &> logs/configure.log || return

   make install

4) GCC Final
   make all
   make install

Any help / pointers in this regard will be greatly appreciated.

Thanks in advance,

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