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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 38497CA9EA0 for ; Fri, 18 Oct 2019 21:01:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0B3A52089C for ; Fri, 18 Oct 2019 21:01:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2502528AbfJRVBx (ORCPT ); Fri, 18 Oct 2019 17:01:53 -0400 Received: from gate.crashing.org ([63.228.1.57]:40170 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728410AbfJRVBw (ORCPT ); Fri, 18 Oct 2019 17:01:52 -0400 Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id x9IK2BmA030151; Fri, 18 Oct 2019 15:02:11 -0500 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id x9IK2AiY030150; Fri, 18 Oct 2019 15:02:10 -0500 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Fri, 18 Oct 2019 15:02:10 -0500 From: Segher Boessenkool To: Nathan Chancellor Cc: Nick Desaulniers , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , clang-built-linux , linuxppc-dev , LKML Subject: Re: [PATCH v4 3/3] powerpc/prom_init: Use -ffreestanding to avoid a reference to bcmp Message-ID: <20191018200210.GR28442@gate.crashing.org> References: <20190911182049.77853-1-natechancellor@gmail.com> <20191014025101.18567-1-natechancellor@gmail.com> <20191014025101.18567-4-natechancellor@gmail.com> <20191014093501.GE28442@gate.crashing.org> <20191014191141.GK28442@gate.crashing.org> <20191018190022.GA1292@ubuntu-m2-xlarge-x86> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191018190022.GA1292@ubuntu-m2-xlarge-x86> User-Agent: Mutt/1.4.2.3i Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 18, 2019 at 12:00:22PM -0700, Nathan Chancellor wrote: > Just as an FYI, there was some more discussion around the availablity > and use of bcmp in this LLVM bug which spawned > commit 5f074f3e192f ("lib/string.c: implement a basic bcmp"). > > https://bugs.llvm.org/show_bug.cgi?id=41035#c13 > > I believe this is the proper solution but I am fine with whatever works, > I just want our CI to be green without any out of tree patches again... I think the proper solution is for the kernel to *do* use -ffreestanding, and then somehow tell the kernel that memcpy etc. are the standard functions. A freestanding GCC already requires memcpy, memmove, memset, memcmp, and sometimes abort to exist and do the standard thing; why cannot programs then also rely on it to be the standard functions. What exact functions are the reason the kernel does not use -ffreestanding? Is it just memcpy? Is more wanted? Segher