Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752754AbdHKJej (ORCPT ); Fri, 11 Aug 2017 05:34:39 -0400 Received: from mail-oi0-f65.google.com ([209.85.218.65]:32899 "EHLO mail-oi0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751416AbdHKJeh (ORCPT ); Fri, 11 Aug 2017 05:34:37 -0400 MIME-Version: 1.0 In-Reply-To: References: <20170811092213.mdmzqtm2lp6ltlxt@armageddon.cambridge.arm.com> From: Arnd Bergmann Date: Fri, 11 Aug 2017 11:34:36 +0200 X-Google-Sender-Auth: _xv2DcEOASMGUlGsjVh7qPq3tcY Message-ID: Subject: Re: New assembler warnings with binutils 2.29 To: Ard Biesheuvel Cc: Catalin Marinas , Laura Abbott , Will Deacon , Linux Kernel Mailing List , linux-arm-kernel , Michael Collison Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1567 Lines: 42 On Fri, Aug 11, 2017 at 11:26 AM, Ard Biesheuvel wrote: > On 11 August 2017 at 10:22, Catalin Marinas wrote: >> On Thu, Aug 10, 2017 at 01:13:22PM -0700, Laura Abbott wrote: >>> Fedora rawhide recently upgraded to binutils 2.29 and this seems >>> to produce new warnings: >>> >>> ./arch/arm64/include/asm/assembler.h: Assembler messages: >>> ./arch/arm64/include/asm/assembler.h:125: Warning: ignoring attempt to redefine built-in register 'lr' >>> >>> This is >>> >>> /* >>> * Register aliases. >>> */ >>> lr .req x30 // link register >> >> Strange, does gas now think 'lr' is a general purpose register (aliased >> to x30)? It never was and IIRC the toolchain people many years ago >> refused to add it, hence the alias above in the kernel. I wonder if they >> added 'fp' as well... >> >> We could remove the alias and replace all 'lr' instances with 'x30' >> throughout the kernel (no too many) or we add some #ifdef around the >> above based on the binutils version. >> > > This is annoying. Replacing x30 with lr achieves the opposite of the > intent of the binutils change. And using #ifdefs is inaccurate, > because you can't really test the binutils version only the GCC > version, and those are not tightly coupled. > > Can you .unreq it? adding the author of the change to cc https://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=62e20ed45e3da5f3ba695e4ee109317668180fe6 There probably was some reasoning behind the change and an intended method for using it. Arnd