From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicholas Piggin Subject: Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures Date: Thu, 4 Aug 2016 23:54:18 +1000 Message-ID: <20160804235418.1f235f55@roar.ozlabs.ibm.com> References: <1880505.MpH3ISbtMJ@wuerfel> <20160804214713.4baa832e@roar.ozlabs.ibm.com> <4007331.2ypSqpxHsb@wuerfel> <20160804223139.0196b3aa@roar.ozlabs.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20160804223139.0196b3aa@roar.ozlabs.ibm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+glppe-linuxppc-embedded-2=m.gmane.org@lists.ozlabs.org Sender: "Linuxppc-dev" To: Arnd Bergmann Cc: Stephen Rothwell , Nicolas Pitre , "linux-kernel@vger.kernel.org" , "Luis R. Rodriguez" , linux-next@vger.kernel.org, Paul Mackerras , Fengguang Wu , linuxppc-dev@lists.ozlabs.org, Guenter Roeck List-Id: linux-next.vger.kernel.org On Thu, 4 Aug 2016 22:31:39 +1000 Nicholas Piggin wrote: > On Thu, 04 Aug 2016 14:09:02 +0200 > Arnd Bergmann wrote: > > Nicolas Pitre has done some related work, adding him to Cc. IIRC we have > > actually had multiple implementations of -ffunction-sections/--gc-sections > > in the past that people have used in production, but none of them > > ever made it upstream. After some googling around it seems lto has been difficult to get in and it was agreed this gc-sections should be done first anyway (although it may indeed provide a superset of DCE, but it's always going to be more costly and complicated). Lto would have the same issue with liveness of entry points, which is really the only thing you need change in the kernel as far as I can see. I didn't really see what problems people were having with it though, so maybe it's architecture specific or something I haven't run into yet. Thanks, Nick