Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751629AbbLUM6d (ORCPT ); Mon, 21 Dec 2015 07:58:33 -0500 Received: from mail-yk0-f179.google.com ([209.85.160.179]:35781 "EHLO mail-yk0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750965AbbLUM6b (ORCPT ); Mon, 21 Dec 2015 07:58:31 -0500 MIME-Version: 1.0 In-Reply-To: <20151221125130.GO23092@arm.com> References: <1450498655-3820-1-git-send-email-apinski@cavium.com> <20151221123843.GM23092@arm.com> <20151221125130.GO23092@arm.com> Date: Mon, 21 Dec 2015 13:58:30 +0100 Message-ID: Subject: Re: [PATCH] ARM64: Fix compiling with GCC 6 and Atomics enabled From: Ard Biesheuvel To: Will Deacon Cc: Andrew Pinski , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" 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: 1674 Lines: 36 On 21 December 2015 at 13:51, Will Deacon wrote: > On Mon, Dec 21, 2015 at 01:46:22PM +0100, Ard Biesheuvel wrote: >> On 21 December 2015 at 13:38, Will Deacon wrote: >> > On Fri, Dec 18, 2015 at 08:17:35PM -0800, Andrew Pinski wrote: >> >> The problem here is that GCC 6 and above emits .arch now >> >> for each function so now the global .arch_extension has >> >> no effect. This fixes the problem by putting >> >> .arch_extension inside ARM64_LSE_ATOMIC_INSN so >> >> it is enabled for each place where LSE is used. >> > >> > Hmm, this is going to affect arch/arm/ much more heavily than arch/arm64. >> > .arch_extension is used for virt, mp and sec over there, and it may be >> > tricky to isolate the actual instruction usage (at least, virt looks >> > lost in kvm/arm.c). >> > >> > Why can't gas have an option to accept all instruction encodings that it >> > knows about, inspite of any .arch directives? >> > >> >> Modern GAS supports things like -march=armv7-a+mp+sec+virt, so it >> probably makes sense to pass that on the command line when building >> for v7 (or +sec only for v6) if the assembler is found to support it >> at build time. > > Does that override a more restrictive .arch directive emitted by the > compiler? > It seems to be additive: -march=armv7-a+mp+sec allows a .S file containing a virt arch_extension + both hvc and smc instructions to be assembled. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/