From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures Date: Thu, 04 Aug 2016 17:43:20 +0200 Message-ID: <2145682.qktvngUhUu@wuerfel> References: <20160804223139.0196b3aa@roar.ozlabs.ibm.com> <20160804235418.1f235f55@roar.ozlabs.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: <20160804235418.1f235f55@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: Nicholas Piggin 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 Thursday, August 4, 2016 11:54:18 PM CEST Nicholas Piggin wrote: > 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. Ok, good. > 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. I remember trying it a few years ago without success, it's possible that old binutils versions were more problematic. I'm happy to test your patches on ARM, with my randconfig builder I tend to find obscure bugs in corner cases that you might not normally find with just defconfig/allmodconfig builds. Arnd