ARM Cortex-M Microcontroller startup files

[Timo Sintonen via Digitalmars-d]

On Sunday, 26 April 2015 at 18:23:47 UTC, Martin Nowak wrote:

> The wiki says to disable multilib
> (http://wiki.dlang.org/Bare_Metal_ARM_Cortex-M_GDC_Cross_Compiler#Build_GCC),
> what's the problem? Maybe ask Iain/Johannes if it's GDC 
> specific.

I have also tried for years to build a working multilib without 
success. Now I think I have been able to get all versions to 
work. I welcome everyone to test and report if this works.

The build script:
../gcc/configure --disable-bootstrap \
--enable-languages=c,d  --disable-nls --target=arm-eabi \
--without-headers  --with-newlib --without-isl --without-cloog \
--disable-libphobos --disable-libstdcxx --disable-libbacktrace\
--enable-multilib

And I replace the whole gcc/config/arm/t-arm-elf with this:
MULTILIB_OPTIONS  += mcpu=cortex-m0/mcpu=cortex-m3/mcpu=cortex-m4 
  mfloat-abi=hard mfpu=fpv4-sp-d16
MULTILIB_DIRNAMES += cortex-m0 cortex-m3 cortex-m4
MULTILIB_REQUIRED += mcpu=cortex-m0
MULTILIB_REQUIRED += mcpu=cortex-m3
MULTILIB_REQUIRED += mcpu=cortex-m4 #/mfloat-abi=hard  
#/mfpu=fpv4-sp-d16
MULTILIB_EXTRA_OPTS += mthumb


This will build m0 and m3 with soft float and m4 with hard float. 
I have used gdc head + gcc 6 head from about a week ago. It may 
be possible this will work with gcc 5.1 release + gdc 5  and I 
hope somebody will test this.

Please note: This is the first time ever I have suceeded. This 
will not work with any gcc before april. An older gcc will not 
build m4 or it may even not pass configuring.

So please test and report.

>
> What libc are you using? The gcc-arm-embedded project uses 
> newlib and
> newlib-nano. https://launchpad.net/gcc-arm-embedded

I have used standard newlib from sources. There were some 
discussions that libc should not be needed any more to build the 
compiler. I can not test this because I do not have a totally 
clean environment right now. So if anybody could advice me or 
just test if it is currently possible to build without libc.