ctcbuild

A GCC cross toolchain builder script, with a special focus on Ada on ARM Cortex-M devices.

GCC documentation states:

In order to build a cross compiler, it is strongly recommended to install the new compiler as native first, and then use it to build the cross compiler. Other native compiler versions may work but this is not guaranteed and will typically fail with hard to understand compilation errors during the build.

Basically what this script tries to automate is the following recipe:

1. Build native GCC and binutils (as and ld)
2. Build native libgcc, libstdc++ and libada (for compiling cross-GNAT)
3. Install native toolchain
4. Build stage1 cross GCC and binutils (as and ld)
5. Install stage1 GCC and binutils
6. Build and install newlib
7. Build stage2 cross GCC with newlib sysroot
8. Build gdb

Example usage: ./ctcbuild conf/13.1-arm-none-eabi.rm.sh

This is what the directory tree typically looks like after the complete process of building a cross-toolchain is finished.

repo/
tarballs/
builds/
  {CONFIG_ID}/
    sources/
      binutils-2.40/
      gcc-13.1.0/
      gdb-13.2/
      gmp-6.2.1/
      isl-0.24/
      mpc-1.3.1/
      mpfr-4.2.0/
      newlib-4.3.0.20230120/
    build/
      {HOST}/
        gcc-13.1.0/
      {TARGET}/
        stage1/
          gcc-13.1.0/
        stage2/
          newlib-4.3.0.20230120/
          gcc-13.1.0/
    install/
      {HOST}/
        bin/
        lib/
        ...
      {TARGET}/
        stage1/
          bin/
          ...
        stage2/
          bin/
          ...

Configure Options

For starters have a look at the following ressources:

Linaro ABE manifests for the ARM GCC toolchain:

• arm-gnu-toolchain-arm-none-eabi-abe-manifest.txt
• arm-gnu-toolchain-arm-none-eabi-nano-abe-manifest.txt

GCC configure documentation

The following sections describe the configure options outlines in the ABE manifests. In contrast to ABE this script uses a combined tree build as described in the GCC documentation.

GCC

Option	Stage 1	Stage 2
--with-mpc=${local_builds}/destdir/${host}	x	x
--with-mpfr=${local_builds}/destdir/${host}	x	x
--with-gmp=${local_builds}/destdir/${host}	x	x
--disable-libatomic	x	-
--disable-libsanitizer	x	-
--disable-libssp	x	-
--disable-libgomp	x	-
--disable-libmudflap	x	-
--disable-libquadmath	x	-
--disable-shared	x	x
--disable-nls	x	x
--disable-threads	x	x
--disable-tls	x	x
--enable-checking=release	x	x
--enable-languages=c	x	-
--enable-languages=c,c++	-	x
--without-cloog	x	-
--without-isl	x	-
--with-newlib	x	x
--without-headers	x	-
--with-gnu-as	x	x
--with-gnu-ld	x	x
--with-multilib-list=aprofile,rmprofile	x	x
--with-sysroot=${local_builds}/sysroot-arm-none-eabi	x	-
--with-build-sysroot=${sysroots}	-	x
--with-sysroot=${local_builds}/destdir/${host}/arm-none-eabi	-	x

GMP

--enable-cxx --enable-fft

MPFR

--with-gmp=${local_builds}/destdir/${host}

MPC

-with-gmp=${local_builds}/destdir/${host} --with-mpfr=${local_builds}/destdir/${host}

NEWLIB

Option	Newlib	Newlin-Nano
--disable-newlib-supplied-syscalls	x	x
--enable-newlib-reent-check-verify	x	x
--enable-newlib-retargetable-locking	x	x
--enable-newlib-io-long-long	x	-
--enable-newlib-io-c99-formats	x	-
--enable-newlib-mb	x	-
--enable-newlib-register-fini	x	-
--disable-newlib-fseek-optimization	-	x
--disable-newlib-fvwrite-in-streamio	-	x
--disable-newlib-unbuf-stream-opt	-	x
--disable-newlib-wide-orient	-	x
--enable-lite-exit	-	x
--enable-newlib-global-atexit	-	x
--enable-newlib-nano-formatted-io	-	x
--enable-newlib-nano-malloc	-	x
--enable-newlib-reent-small	-	x

binutils

--enable-initfini-array --disable-nls --without-x --disable-gdbtk --without-tcl --without-tk --enable-plugins --disable-gdb --without-gdb --with-sysroot=${sysroots}

gdb

--with-gnu-ld --enable-plugins --enable-tui --with-pkgversion=Linaro_GDB-2019.12 --disable-gas --disable-binutils --disable-ld --disable-gold --disable-gprof --with-python=yes

Building gnattols without libada

When building a bare-metal toolchain, there will typically be no Ada runtime system available, thus the compiler cannot produce executables for the target yet. Therefore it is not possible to build the libada GCC make target. Building the gnattools should not depend on libada but for some reason, when libada is added to the Makefile by the configure script, when gnattols is selected.

The AVR-Ada project solves this by patching the gcc configure script: https://github.com/johnleimon/avr-ada/blob/master/avr-ada/patches/gcc/4.9.2/23-gcc-4.9-ada-Makefile.patch

Since gprconfig searches for the 'gnat' executable, it seems like a good idead to have the gnattols available.