Re: Building Linux x86_64 to AIX PowerPC cross-compiler

[Brian Groose <brian@groose.com>]

On Wed, Jun 15, 2022 at 7:37 AM Kai Ruottu <kai.ruottu@wippies.com> wrote:
>
> Paul Lucas via Gcc-help kirjoitti 14.6.2022 klo 19.18:
> > Hi there -
> >
> > I want to build a cross-compiler from Linux x86_64 (host) to AIX PowerPC (target).  Eventually, while building gcc, I get:
> >
> >> collect2: fatal error: libgcc.a: cannot open as COFF file
> >
> > While Linux uses ELF and AIX uses coff, I would have assumed that the binutils I built for the cross-compiler would have produced a linker that was able to link COFF files.
> >
> > The configure for binutils was:
> >
> >> configure --disable-gold --prefix=/aix-powerpc --disable-multilib --disable-nls --target=powerpc-ibm-aix7.1.0.0 --with-sysroot=/aix-powerpc --with-arch=powerpc --disable-werror --enable-plugins
> > where /aix-powerpc contains headers and libraries copied from a live AIX system.
>
>
> The GNU Install documents for target platforms :
>
> https://gcc.gnu.org/install/specific.html#x-ibm-aix
>
> are saying :
>
> "The native |as| and |ld| are recommended for bootstrapping on AIX. The
> GNU Assembler, GNU Linker, and GNU Binutils version 2.20 is the minimum
> level that supports bootstrap on AIX 5. The GNU Assembler has not been
> updated to support AIX 6 or AIX 7. The native AIX tools do interoperate
> with GCC."
>
> So it seems that AIX 6 and AIX 7 aren't supported in GNU binutils :(
>
> The biggest problem in this issue probaly is that so few people can get
> the "headers and libraries copied from a live AIX system". Or IBM or
> something would provide them freely
> for everyone wanting to make crosscompilers for AIX. Those who have AIX
> systems just produce native GNU tools and are happy. Others aren't
> interested to work with cross
> tools they cannot make...
> For instance the Sun Solaris2 headers and libraries have beem freely
> available just like the whole Sparc/x86 operating systems. So anyone
> could have procuded crosstools for these
> platforms if having the required know-how for building GNU tools.

I had also tried to get a Linux x86_64 cross compiler targeting AIX 6.1 several
years ago and was never able to make it work, the issue was always binutils
and not gcc.  Even when I compiled native binutils and gcc on AIX 6.1 I ended
up using the AIX versions of as/ld/ar/etc since they worked more reliably than
the binutils versions.  I eventually gave up on a cross compiler and continued
to natively compile, though cross compilation would have been a much nicer and
more scalable system.

I recall bumping into the docs that Kai quoted here, which confirmed
that it just
wasn't going to work since there was effectively no assembler that worked.