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From:   Nick Desaulniers <ndesaulniers@google.com>
Date:   Tue, 31 Mar 2020 12:40:42 -0700
Message-ID: <CAKwvOdnY64uo=73P2qkJkMbFxPTX8v7gC0cfxFndpaqsQ_c-CQ@mail.gmail.com>
Subject: Re: [PATCH v2] Makefile.llvm: simplify LLVM build
To:     Nathan Chancellor <natechancellor@gmail.com>
Cc:     Masahiro Yamada <masahiroy@kernel.org>,
        clang-built-linux <clang-built-linux@googlegroups.com>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Sandeep Patil <sspatil@google.com>
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On Tue, Mar 31, 2020 at 12:35 PM Nathan Chancellor
<natechancellor@gmail.com> wrote:
>
> On Tue, Mar 31, 2020 at 11:39:27AM -0700, Nick Desaulniers wrote:
> > On Mon, Mar 30, 2020 at 11:25 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
> > >
> > > In fact, the debian provides multiple versions of GCC.
> > > For example, my machine has
> > >
> > > masahiro@pug:~$ ls -1 /usr/bin/gcc-*
> > > /usr/bin/gcc-4.8
> > > /usr/bin/gcc-5
> > > /usr/bin/gcc-7
> > > /usr/bin/gcc-ar
> > > /usr/bin/gcc-ar-4.8
> > > /usr/bin/gcc-ar-5
> > > /usr/bin/gcc-ar-7
> > > /usr/bin/gcc-nm
> > > /usr/bin/gcc-nm-4.8
> > > /usr/bin/gcc-nm-5
> > > /usr/bin/gcc-nm-7
> > > /usr/bin/gcc-ranlib
> > > /usr/bin/gcc-ranlib-4.8
> > > /usr/bin/gcc-ranlib-5
> > > /usr/bin/gcc-ranlib-7
> > >
> > > But, nobody has suggested GCC_SUFFIX.
> > >
> > > So, I guess CROSS_COMPILE was enough to
> > > choose a specific tool version.
> >
> > Or no one was testing specific versions of gcc with more than one
> > installed.  I can ask the KernelCI folks next week if this is an issue
> > they face or have faced.
>
> Well gcc is just one tool, so specified CC=gcc-5 is not that
> complicated; it would get a lot more gnarly if one had different
> versions of binutils as well.

Have you had to test different releases of binutils yet? I have, and
it was not fun.  I don't even remember what I did but I recall it
being painful trying to get it to work.  (I think I finally solved it
via temporary symlink).  Speaking of, I should get back to those
dwarf-5 patches I started, now that binutils devs implemented every
missing feature I could find.
-- 
Thanks,
~Nick Desaulniers