Building llvm toolchain for RTEMS

[Hesham Almatary]

Hello Jan,

Unlike GCC, LLVM/Clang only gives you one toolchain for all backend
architectures (depending on how you configured it). You'll also need
to tell LLVM/Clang where to find the sysroot to pick newlib and
builtins headers/libs. GCC does that automatically for you, but
LLVM/Clang does not. You can either point LLVM/Clang to the
GCC-installed sysroot/multilib, or to manually/separately build newlib
(libc) and compiler-rt (which corresponds to libgcc) on your own.

I have only tested building RTEMS with LLVM/Clang on RISC-V platforms,
but I build my own LLVM/Clang, newlib, compiler-rt toolchain/sysroot,
not from RSB.

On Wed, 26 May 2021 at 11:57, <Jan.Sommer at dlr.de> wrote:
>
> Ok, I build the llvm buildset with RSB and then tried to set the COMPILER option in the ini file for the BSP, but that did not work.
> Is it only available for certain BSPs or am I completely of the track?
>
> Best regards,
>
>     Jan
>
> > -----Original Message-----
> > From: devel <devel-bounces at rtems.org> On Behalf Of Jan.Sommer at dlr.de
> > Sent: Friday, May 21, 2021 12:25 PM
> > To: devel at rtems.org
> > Subject: Building llvm toolchain for RTEMS
> >
> > Hello,
> >
> > I see some references to llvm toolchains for RTEMS from time to time, but
> > haven't really looked into it.
> > Is it possible to let RSB build a clang C/C++ compiler and kernel for e.g. the
> > Zedboard BSP?
> > If yes, how would I build such a toolchain? I see that there is a llvm buildset in
> > RSB, but it doesn't seem architecture specific.
> >
> > Best regards,
> >
> >     Jan
> >
> > Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR) German Aerospace
> > Center Institute for Software Technology | Software for Space Systems and
> > Interactive Visualization | Lilienthalplatz 7 | 38108 Braunschweig | Germany
> >
> > Jan Sommer
> > Telephone +49 531 295-2494 | Telefax 0531 295-2767 | jan.sommer at dlr.de
> > DLR.de/SC
> >
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