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Date:   Mon, 10 Jun 2019 16:48:58 +0200
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Cc:     Ignat Korchagin <ignat@cloudflare.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>
Subject: Re: Linux 4.19 and GCC 9
Message-ID: <20190610144858.GA1481@kroah.com>
References: <20190517085126.GA3249@kroah.com>
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On Mon, Jun 10, 2019 at 04:42:27PM +0200, Miguel Ojeda wrote:
> On Mon, Jun 10, 2019 at 4:21 PM Greg KH <gregkh@linuxfoundation.org> wrote:
> >
> > > I also checked that 4.19.49 compiles fine with GCC 9, although with a
> > > lot of warnings, mostly from objtool, like "warning: objtool:
> > > sock_register()+0xd: sibling call from callable instruction with
> > > modified stack frame". But it's a start.
> 
> I think Josh Poimboeuf added support for a few related things in GCC 8
> (e.g. 13810435b9a7 ("objtool: Support GCC 8's cold subfunctions")).

That commit is already in all stable releases, so does there need to be
a gcc 9 specific one?

> > I'll look into these after the next round of kernels are released.  I
> > guess I'll go find a distro that has gcc9 on it to actually test
> > things...
> 
> 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".

thanks,

greg k-h