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From:   Ignat Korchagin <ignat@cloudflare.com>
Date:   Mon, 10 Jun 2019 16:01:56 +0100
Message-ID: <CALrw=nEFtg47p0WZrDVWGcRZDqgA-x_ADXe5-TA92hB6W8zYtQ@mail.gmail.com>
Subject: Re: Linux 4.19 and GCC 9
To:     Greg KH <gregkh@linuxfoundation.org>
Cc:     Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
        Ivan Babrou <ivan@cloudflare.com>,
        Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Ingo Molnar <mingo@redhat.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@redhat.com>,
        Namhyung Kim <namhyung@kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        kernel-team <kernel-team@cloudflare.com>
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On Mon, Jun 10, 2019 at 3:49 PM Greg KH <gregkh@linuxfoundation.org> wrote:
>
> >
> > I typically compile a bare-bones GCC for those things, it is quite quick.
>
> Pointers to how to do that is appreciated.  It's been years since I had
> to build gcc "from scratch".

This is how we do it, but we use it for some other projects as well,
so need ligcc and c++ support. I suspect for kernel-only there may be
a more lightweight approach (for example, by dropping c++):

Env: Debian Stretch (we run in a simple official docker container with
build-essential and make installed) - but probably should work on any
distro
Assuming the sources are extracted into $(BUILDDIR)/gcc-$(VERSION)

cd $(BUILDDIR)/gcc-$(VERSION)
./contrib/download_prerequisites
cd ..
mkdir gcc-build
cd gcc-build
../gcc-$(VERSION)/configure --enable-languages=c,c++
--build=x86_64-linux-gnu --disable-multilib
make -j<something>
sudo make install (or install into alternative dir and point Linux
build system there)

Regards,
Ignat