arm-elf-gcc compiling for cortex-M4

Hi Jvanmont,

it would depend on the GCC Compiler version what compile switches are valid. If your compiler supports the switches, you should specify them by lower case letters. That is, -mcpu=cortex-m4 -march=armv7e-m.

Best regards,
Yasuhiko Koumoto.

Hi Jvanmont,

it would depend on the GCC Compiler version what compile switches are valid. If your compiler supports the switches, you should specify them by lower case letters. That is, -mcpu=cortex-m4 -march=armv7e-m.

Best regards,
Yasuhiko Koumoto.

Hi jvanmont - sorry for the late reply.

I use gcc-4.8.3 myself; I can use the same arm-none-eabi-gcc to build for Cortex-M0, Cortex-M3 and Cortex-M4.

Building gcc-4.8.3 is a bit more difficult than building a v4.5 and earlier.

-I recommend getting the launchpad version, if you're able to build it. The only reason I had to build my own, is that I'm on a PowerPC based Mac, which none of the well-known toolchains will work for.

If you are using a PowerMac (not Mac Pro), please let me know.

In order to use the --with-multilib-list, you will need to apply two patches: t-arm-elf.patch and cortex-m0-trap.S.patch (they're attached to this post).

If you want to build gcc-4.8.3, then I'll give you some hints for preparing the sources.

To build gcc, do not compile mpfr, mpc and gmp; instead make symlinks to the parent directories, otherwise you'll be waiting half a day until it's built.

If you're building for Mac (or your /usr directory is not writable by you), then you'll need to prefix the 'make install' by sudo.

I also recommend using parallel-builds to save you 3-4 hours.

For instance 'make -j8' instead of just 'make'. The number after -j is twice the number of cores that your computer has.

Patch sources, so we'll get support for all Cortex-M architectures (and ARM7TDMI):

( cd "source/gcc-4.8.3/"; patch -p1 < "archives/t-arm-elf.patch" )

( cd "source/newlib-2.1.0/"; patch -p1 < "archives/cortex-m0-trap.S.patch" )

Create symlinks to used libraries:

ln -s "source/gmp-5.1.3" "source/gcc-4.8.3/gmp"

ln -s "source/mpfr-3.1.2" "source/gcc-4.8.3/mpfr"

ln -s "source/mpc-1.0.2" "source/gcc-4.8.3/mpc"

ln -s "source/libelf-0.8.13" "source/gcc-4.8.3/libelf"

ln -s "source/newlib-2.1.0/newlib" "source/gcc-4.8.3/newlib"

These are my build-lines for binutils:

./configure --target=arm-none-eabi --prefix=/usr/local/arm-none-eabi --disable-nls --disable-libssp --with-gcc --with-gnu-as --with-gnu-ld --enable-multilib --enable-interwork --enable-plugins --with-system-zlib

make && make install

My build-lines for bootstrap gcc:

./configure --target=arm-none-eabi --prefix=/usr/local/arm-none-eabi --disable-nls --with-gcc --with-gnu-as --with-gnu-ld --with-dwarf2 --enable-multilib --enable-interwork --with-newlib --disable-libssp --with-system-zlib --disable-decimal-float --disable-libffi --disable-libmudflap --with-multilib-list=armv6-m,armv7-m,armv7e-m,armv7-r --disable-libstdcxx-pch --without-headers --enable-languages="c,c++"

make all-gcc && make install-gcc

Temporarily add the newly built gcc to the PATH environment variable:

export PATH="$PATH:/usr/local/arm-none-eabi/bin"

My build-lines for newlib:

./configure --target=arm-none-eabi --prefix=/usr/local/arm-none-eabi --enable-interwork --enable-multilib --disable-libssp --disable-nls --enable-newlib-io-long-long --enable-newlib-register-fini --disable-newlib-supplied-syscalls

make CFLAGS_FOR_TARGET="-D__IEEE_BIG_ENDIAN -D__IEEE_BYTES_LITTLE_ENDIAN -D__BUFSIZ__=64" && env "PATH=$PATH" make install || env "PATH=$PATH" make install

(yes, the crazy double-install is most likely necessary, because a directory is missing on the first try)

Show the architectures that your multilib supports; this should include all Cortex-M, plus ARM7TDMI:

arm-none-eabi-gcc -print-multi-lib

My build-lines for final gcc:

./configure --target=arm-none-eabi --prefix=/usr/local/arm-none-eabi --disable-nls --with-gcc --with-gnu-as --with-gnu-ld --with-dwarf2 --enable-multilib --enable-interwork --with-newlib --disable-libssp --with-system-zlib --disable-decimal-float --disable-libffi --disable-libmudflap --with-multilib-list=armv6-m,armv7-m,armv7e-m,armv7-r --disable-libstdcxx-pch --with-headers=yes --enable-languages="c,c++"

make all -Wno-error=deprecated-declarations && make install

If you need more information, please send me a personal message.

yasuhikokoumoto The toolchain can be picked from this source GCC ARM Embedded in Launchpad

It builds for cortex-M under cygwin env with make.