Building upstream RISC-V GCC+binutils+newlib: the quick and dirty way

There are a number of available options for building a RISC-V GCC toolchain. You might use the build system from the riscv/riscv-tools repository, or investigate toolchain generators such as crosstool-ng. However in the case of riscv-tools, it’s not always clear how this corresponds to the code in the relevant upstream projects. When investigating a potential bug, you often just want to build the latest upstream code with as little fuss as possible. For distribution purposes you’d probably want to perform a proper multi-stage build, but for a quick test you might find the following recipe useful:

git clone --depth=1 git://gcc.gnu.org/git/gcc.git gcc
git clone --depth=1 git://sourceware.org/git/binutils-gdb.git
git clone --depth=1 git://sourceware.org/git/newlib-cygwin.git
mkdir combined
cd combined
ln -s ../newlib-cygwin/* .
ln --force -s ../binutils-gdb/* .
ln --force -s ../gcc/* .
mkdir build
cd build
../configure --target=riscv32-unknown-elf --enable-languages=c \
--disable-shared --disable-threads --disable-multilib --disable-gdb \
--disable-libssp --with-newlib \
--with-arch=rv32ima --with-abi=ilp32 --prefix=$(pwd)/built
make -j
make install

This will produce a newlib toolchain targeting RV32IMA in the built/ subdirectory. When files are duplicated in the newlib, binutils and gcc repositories, the gcc version takes precedence.

Major credit to everyone who worked on getting these toolchain ports upstream (Kito Cheng, Palmer Dabbelt, and others).