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Date: Thu, 11 Jan 2018 18:05:24 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Jiri Kosina <jikos@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
        David Woodhouse <dwmw2@infradead.org>, x86@kernel.org,
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Subject: Re: [PATCH 2/3] objtool: Ignore retpoline alternatives
Message-ID: <20180111170524.GH6176@hirez.programming.kicks-ass.net>
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On Thu, Jan 11, 2018 at 06:01:23PM +0100, Jiri Kosina wrote:
> On Thu, 11 Jan 2018, Josh Poimboeuf wrote:
> 
> > I think I heard that retpolines won't be ported to anything older than 
> > GCC 4.9, so maybe it's safe to use '%='.  I don't remember when it was 
> > introduced into GCC though.
> 
> I'm afraid we'll have to backport retpolines in some form to 4.3.x at 
> least. I'd be surprised if we'd be the only ones on this planet :)

So upstream code is going to require 4.5 at least, and 4.4 has %=.
Backport effort will just have to cope or backport more GCC bits, that
is, if you're backporting retpoline to 4.3 also backport asm-goto.