Compiling newlib for the msp430x architecture

Compiling newlib for the msp430x architecture

[Stephan]

Hello,

I failed to compile newlib for with the msp430x architecture with 92kB 
Flash.

Trying to compile newlib (in my case for the MSP430F2617) with the large 
memory model (20bit pointers) failed for me because the Make-System 
automatically injected the -mcpu=msp430 into the gcc flags. This gives 
me the following warning:

 > ../../../../../../newlib/libc/argz/dummy.c:1:0: warning: MCU 
'msp430f2617' supports 430X ISA but -mcpu option is set to 430

because in order to get the large memory addressing instructions you 
need to set -mlarge which requires the -mmcu=msp430f2617 option.

I tried to debug this as i thought it was my fault but it turns out that 
some Makefile extracts the -mcpu=msp430 option from the

$ msp430-elf-gcc /* couple of -L and -B's */ --print-multi-lib

command. According to the GCC manpage this option is deprecated and 
-mmcu= should be used instead.

I'm not sure if I am missing something here or if this is really a bug 
in the make system which is why I am asking here.

Thanks, Stephan

Re: Compiling newlib for the msp430x architecture

[Nick Clifton]

Hi Stephan,

> I tried to debug this as i thought it was my fault but it turns out that some Makefile extracts the -mcpu=msp430 option from the
> 
> $ msp430-elf-gcc /* couple of -L and -B's */ --print-multi-lib

Which Makefile does this ?

Cheers
  Nick

Re: Compiling newlib for the msp430x architecture

[Nick Clifton]

Hi Stephan,

> found it, it's config-ml.in, target (?) multi-do: line 491 (for me). Which results in the target multi-do: line 1246 in the build/msp430-elf/newlib/Makefile.

Ah - right - so you are trying to build newlib specifically for the 320F2617 
but you are using a compiler that has been created with multilib support
enabled, so the config-ml.in script is trying to create separate builds for
each of the different multilibs supported by gcc.

Is there any reason why you want to build newlib specifically for the 320F2617 ?
Won't the generic -mlarge multilib version of the newlib just work for you ?

Cheers
  Nick

Re: Compiling newlib for the msp430x architecture

[Nick Clifton]

Hi Stephan,

> But I am not sure what you mean with the generic -mlarge multilib version. Is it automatically built alongside the -msmall (default i think) version?

Yes.

What should happen is that the compiler (gcc) should automatically choose 
the correct version of the standard libraries to use when building your
application.  So, suppose you compile a program with "-mmcu=msp430f2617 -mlarge"
specified on the command line, gcc should automatically recognise this as
requiring a -mlarge compatible version of the C library and select that version
when linking your program.

Different versions of the same library are held in different sub-directories of
the installation directory.  So for example the -mlarge version of the C library
should be in the large/ sub-directory of /usr/lib.  (Or wherever the libraries
have been installed).  All of this should be transparent to the programmer.  You
should not need to know about it.  You just compile and link your application
and the correct libraries are automatically selected by the gcc driver.

The problem comes when you try to build your own version of these standard libraries.
Ideally you would just build them using the standard "configure ; make" process,
but for some reason you are trying to force a specific MCU selection and this is
causing the problems.  And my question to you is - why are you trying to do this ?


> The compiler is the bare gcc toolchain from TI if that helps.

Does the toolchain from TI not come with the (multiple versions of the) C library 
already built ?

Cheers
  Nick