From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D186FC32792 for ; Thu, 3 Oct 2019 16:16:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 930A7215EA for ; Thu, 3 Oct 2019 16:16:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389010AbfJCQQb (ORCPT ); Thu, 3 Oct 2019 12:16:31 -0400 Received: from foss.arm.com ([217.140.110.172]:48430 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388982AbfJCQQZ (ORCPT ); Thu, 3 Oct 2019 12:16:25 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9C54E1000; Thu, 3 Oct 2019 09:16:24 -0700 (PDT) Received: from arrakis.emea.arm.com (unknown [10.1.196.49]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7EFC23F739; Thu, 3 Oct 2019 09:16:23 -0700 (PDT) Date: Thu, 3 Oct 2019 17:16:21 +0100 From: Catalin Marinas To: Vincenzo Frascino Cc: ard.biesheuvel@linaro.org, ndesaulniers@google.com, linux-kernel@vger.kernel.org, luto@kernel.org, tglx@linutronix.de, will@kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v4 1/6] arm64: vdso32: Fix syncconfig errors. Message-ID: <20191003161621.GJ21629@arrakis.emea.arm.com> References: <20191002144156.2174-1-vincenzo.frascino@arm.com> <20191002144156.2174-2-vincenzo.frascino@arm.com> <20191003160041.GI21629@arrakis.emea.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191003160041.GI21629@arrakis.emea.arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 03, 2019 at 05:00:41PM +0100, Catalin Marinas wrote: > On Wed, Oct 02, 2019 at 03:41:51PM +0100, Vincenzo Frascino wrote: > > diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile > > index 84a3d502c5a5..dfa6a5cb99e4 100644 > > --- a/arch/arm64/Makefile > > +++ b/arch/arm64/Makefile > > @@ -53,20 +53,12 @@ $(warning Detected assembler with broken .inst; disassembly will be unreliable) > > endif > > endif > > > > +COMPATCC ?= $(CROSS_COMPILE_COMPAT)gcc > > +export COMPATCC > > + > > ifeq ($(CONFIG_GENERIC_COMPAT_VDSO), y) > > - CROSS_COMPILE_COMPAT ?= $(CONFIG_CROSS_COMPILE_COMPAT_VDSO:"%"=%) > > - > > - ifeq ($(CONFIG_CC_IS_CLANG), y) > > - $(warning CROSS_COMPILE_COMPAT is clang, the compat vDSO will not be built) > > - else ifeq ($(strip $(CROSS_COMPILE_COMPAT)),) > > - $(warning CROSS_COMPILE_COMPAT not defined or empty, the compat vDSO will not be built) > > - else ifeq ($(shell which $(CROSS_COMPILE_COMPAT)gcc 2> /dev/null),) > > - $(error $(CROSS_COMPILE_COMPAT)gcc not found, check CROSS_COMPILE_COMPAT) > > - else > > - export CROSS_COMPILE_COMPAT > > - export CONFIG_COMPAT_VDSO := y > > - compat_vdso := -DCONFIG_COMPAT_VDSO=1 > > - endif > > + export CONFIG_COMPAT_VDSO := y > > + compat_vdso := -DCONFIG_COMPAT_VDSO=1 > > endif > > With this change, if I don't have any CROSS_COMPILE_COMPAT in my > environment, the kernel fails to build because COMPATCC becomes gcc > which cannot build the vdso32. What I really want is not to warn me, nor > fail to build the kernel when I don't care about the compat vDSO (e.g. I > have a 64-bit only machine). > > What saved us before was the COMPATCC_IS_ARM_GCC check and a selection > of the GENERIC_COMPAT_VDSO dependent on this check. This was now dropped > from the previous version of the patch. We could add something like > COMPATCC_CAN_LINK. Ah, the COMPATCC_CAN_LINK idea doesn't help because an x86 gcc can still link. Maybe only enable CONFIG_COMPAT_VDSO above if CROSS_COMPILE_COMPAT was set. You could move the COMPATCC setting and export under the same 'if' block in the Makefile. -- Catalin