update example configs and add some crossdev examples

Signed-off-by: Steve Arnold <nerdboy@gentoo.org>

1 files changed, 72 insertions, 0 deletions

diff --git a/configs/armv7m-crossdev.txt b/configs/armv7m-crossdev.txt
new file mode 100644
index 0000000..9367f47
--- /dev/null
+++ b/configs/armv7m-crossdev.txt
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+Use crossdev to build a bare-metal (no kernel headers or full eglibc) for
+an ARM Cortex-M4 dev board.  The cortex-m4 is the armv7e-m arch for gcc.
+The Cortex-M4 has a silicon FPU option (VFPv4-SP) of single-precision (SP),
+which is known as a Cortex-M4F.  The Cortex-M4 also includes SIMD DSP
+instructions.
+
+This commands builds binutils/gcc/newlib/gdb; first emerge crossdev-999999,
+then disable any layman/other overlays and enable the output overlay in the
+crossdev command (unless you want the cross-foo overlay to be created in
+the first existing overlay found by crossdev).
+
+Note for newer portage using repos.conf you should use PORTDIR_OVERLAY for
+the output overlay instead of the crossdev argument for ov-output.  Also if
+portage complains about no LIBC defined, you can add ELIBC="newlib" to
+the command line.
+
+USE="hardened multitarget lzma -multilib -openmp -fortran -jit" EXTRA_ECONF="--disable-multilib --disable-libsanitizer --with-arch=armv7e-m --with-tune=cortex-m4 --with-float-abi=hard --with-fpu=fpv4-sp-d16 --with-mode=thumb" crossdev armv7m-hardfloat-eabi --ex-gdb  --show-fail-log  --ov-output /usr/local/cortex-m4
+
+To use the nano-io and nano-malloc config options, use this one:
+
+USE="hardened multitarget lzma -multilib -openmp -fortran -jit" EXTRA_ECONF="--enable-newlib-nano-formatted-io --enable-newlib-nano-malloc --with-newlib --disable-multilib --disable-libsanitizer --with-arch=armv7e-m --with-tune=cortex-m4 --with-float-abi=hard --with-fpu=fpv4-sp-d16 --with-mode=thumb" crossdev armv7m-hardfloat-eabi --abis "aapcs,atpcs" --ex-gdb  --show-fail-log --ov-output /usr/local/cortex-m4
+
+Final command using portage newlib for default stage-1 gcc:
+
+PORTDIR_OVERLAY="/usr/local/cortex-m4 /var/lib/layman/ada" USE="hardened multitarget lzma -multilib -openmp -fortran -jit -vtv" EXTRA_ECONF="--enable-newlib-nano-formatted-io --enable-newlib-nano-malloc --with-newlib --disable-multilib --disable-libsanitizer --with-arch=armv7e-m --with-tune=cortex-m4 --with-float-abi=hard --with-fpu=fpv4-sp-d16 --with-mode=thumb --with-abi=aapcs-linux --enable-libstdcxx-time=no" crossdev --g 5.4.0-r4 -t armv7m-hardfloat-eabi --ex-gdb  --show-fail-log  -v
+
+Using newlib-nano ebuild in local overlay, note newlib-nano enables the above
+two options plus several others:
+
+PORTDIR_OVERLAY="/usr/local/cortex-m4 /var/lib/layman/ada /usr/local/portage" USE="hardened multitarget lzma -multilib -nls -openmp -fortran -jit -vtv" EXTRA_ECONF="--with-newlib --disable-multilib --disable-libsanitizer --with-arch=armv7e-m --with-tune=cortex-m4 --with-float-abi=hard --with-fpu=fpv4-sp-d16 --with-mode=thumb --with-abi=aapcs-linux" crossdev --g 5.4.0-r4 -t armv7m-hardfloat-eabi  --lenv 'USE="newlib-nano"' --ex-gdb  --show-fail-log  -v
+
+2-stage gcc command with crossdev arg for stage 4 with c,c++ and newlib:
+
+PORTDIR_OVERLAY="/usr/local/cortex-m4 /var/lib/layman/ada" USE="-ada hardened multitarget lzma -multilib -nls -openmp -fortran -jit -vtv" EXTRA_ECONF="--with-newlib --disable-multilib --disable-libsanitizer --with-arch=armv7e-m --with-tune=cortex-m4 --with-float-abi=hard --with-fpu=fpv4-sp-d16 --with-mode=thumb --with-abi=aapcs-linux  --enable-libstdcxx-time=no" crossdev --g 5.4.0-r4 -s4 -t armv7m-hardfloat-eabi  --lenv 'USE="newlib-nano"' --ex-gdb  --show-fail-log  -v
+
+Same command as above but with ada support (just no libada)
+
+PORTDIR_OVERLAY="/usr/local/cortex-m4 /var/lib/layman/ada" USE="ada hardened multitarget lzma -multilib -nls -openmp -fortran -jit -vtv" EXTRA_ECONF="--with-newlib --disable-libada --disable-multilib --disable-libsanitizer --with-arch=armv7e-m --with-tune=cortex-m4 --with-float-abi=hard --with-fpu=fpv4-sp-d16 --with-mode=thumb --with-abi=aapcs-linux  --enable-libstdcxx-time=no" crossdev --g 6.4.0 -s4 -t armv7m-hardfloat-eabi --genv 'EXTRA_ECONF="--with-host-libstdcxx=-static-libgcc -Wl,-Bstatic,-lstdc++,-Bdynamic -lm"' --lenv 'USE="newlib-nano"' --ex-gdb  --show-fail-log  -v
+
+Extra upstream config hack for transactional memory related code in
+crtbegin.o, add INHIBIT_LIBC_CFLAGS to EXTRA_ECONF:
+
+--genv 'EXTRA_ECONF="--with-host-libstdcxx=-static-libgcc -Wl,-Bstatic,-lstdc++,-Bdynamic -lm" INHIBIT_LIBC_CFLAGS="-DUSE_TM_CLONE_REGISTRY=0"'
+
+Basic CFLAGS for target builds:
+
+CFLAGS="-mthumb -march=armv7e-m -mtune=cortex-m4 -mabi=aapcs \
+ -mfpu=fpv4-sp-d16 -mfloat-abi=hard -mfp16-format=ieee \
+ -Wa,-mimplicit-it=thumb"
+
+
+Current vendor toolchain produces:
+
+   text    data     bss     dec     hex filename
+ 208576    1112   27888  237576   3a008 _build/nrf52832_xxaa_s132.out
+
+
+Updated toolchain using gcc 5.4.0, newlib 2.4.0, gdb 7.11.1 without libnano*
+but with newlib-nano-formatted-io and newlib-nano-malloc enabled and -Os
+plus -g debug symbols produces:
+
+   text    data     bss     dec     hex filename
+ 129268    1820   28500  159588   26f64 _build/nrf52832_xxaa_s132.out
+
+
+Updated toolchain using slightly more correct (and bloaty) debug flags, where
+DEBUG_BLOAT = -Og -g3 produces:
+
+   text    data     bss     dec     hex filename
+ 145780    1820   28548  176148   2b014 _build/nrf52832_xxaa_s132.out
+
+Roll your own toolchain ftw!