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Date: Mon, 12 Feb 2018 12:52:06 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Kees Cook <keescook@chromium.org>,
	Ulf Magnusson <ulfalizer@gmail.com>,
	Masahiro Yamada <yamada.masahiro@socionext.com>,
	Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Nicolas Pitre <nicolas.pitre@linaro.org>,
	"Luis R . Rodriguez" <mcgrof@suse.com>,
	Randy Dunlap <rdunlap@infradead.org>,
	Sam Ravnborg <sam@ravnborg.org>,
	Michal Marek <michal.lkml@markovi.net>,
	Martin Schwidefsky <schwidefsky@de.ibm.com>,
	Pavel Machek <pavel@ucw.cz>,
	linux-s390 <linux-s390@vger.kernel.org>,
	Jiri Kosina <jkosina@suse.cz>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Tejun Heo <tj@kernel.org>, Ingo Molnar <mingo@kernel.org>,
	"Van De Ven, Arjan" <arjan.van.de.ven@intel.com>,
	Arnd Bergmann <arnd@arndb.de>, David Woodhouse <dwmw@amazon.co.uk>
Subject: Re: [RFC PATCH 4/7] kconfig: support new special property shell=
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On Mon, Feb 12, 2018 at 11:27:25AM +0100, Thomas Gleixner wrote:
> On Mon, 12 Feb 2018, Peter Zijlstra wrote:
> 
> > On Sun, Feb 11, 2018 at 10:13:44AM -0800, Linus Torvalds wrote:
> > 
> > > That actually sounds like we could just
> > > 
> > >  (a) make gcc 4.5 be the minimum required version
> > > 
> > >  (b) actually error out if we find a bad compiler
> > 
> > So the unofficial plan was to enforce asm-goto and -fentry support by
> > hard failure to build, which would get us at gcc-4.6 and then remove all
> 
> Has gcc-4.6 a (planned) retpoline backport? IIRC the cutoff for that was
> gcc 4.9

Official GCC will not do retpoline before 4.9 AFAIK. But if someone
were to want to build a RETPOLINE=n kernel I don't see why we should
mandate retpoline.

Also, distro's have backported retpoline much further back already.