Hosted GCC Cross-Compiler: Difference between revisions

Your previous <tt>i686-elf</tt> toolchain was built using the <tt>--without-headers</tt> configure option. This tells the compiler that there is no standard library and no headers. The libgcc is built with libc support as described above. This requires the standard library headers to be installed into your [[Meaty Skeleton#System Root|system root]] prior to the cross-compiler build.

 

cd $HOME/myos

mkdir -p sysroot

cp -RT libc/include sysroot/usr/include

cp -RT kernel/include sysroot/usr/include

 

'''Note''': Not all <tt>cp(1)</tt> implementations support the <tt>-RT</tt> combination that conveniently merges the contents of one directory into another.

== Binutils ==

 

cd $HOME/src

mkdir build-binutils

make

make install

 

'''--with-sysroot=''' This option tells the compiler where your sysroot is. It is not used during the compilation process, but it is remembered and used when the linker searches for libraries.

== GCC ==

 

cd $HOME/src

mkdir build-gcc

make all-gcc all-target-libgcc

make install-gcc install-target-libgcc

 

'''--with-sysroot=''' This option tells the compiler where your sysroot is. It is used during the libgcc build and is remembered and used when the compiler searches for headers and libraries.

The libstdc++ library was still not built above as it depends on libc as it needs to perform link tests to know about it. The GCC developers have poorly designed the libstdc++ package and it is tied to GCC and must be built as part of GCC, it can't be built on its own without tricks. If you saved your build-gcc directory from earlier, you can continue the process now (otherwise, it will build a full new cross-compiler for no good reason):

 

cd $HOME/src/build-gcc

make all-target-libstdc++-v3

make install-target-libstdc++-v3

 

=== Troubleshooting ===

In case you get an this error (occurs when using newlib):

 

./../../../gcc-11.3.0/libstdc++-v3/libsupc++/new_opa.cc:62:1: error: ‘void* aligned_alloc(std::size_t, std::size_t)’ was declared ‘extern’ and later ‘static’ [-fpermissive]

aligned_alloc (std::size_t al, std::size_t sz)

 

Open the file '''libstdc++-v3/libsupc++/new_opa.cc''' with an editor and remove the "static inline" before in the function prototype.