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 3AFE9CA9EA0 for ; Fri, 18 Oct 2019 20:04:26 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6D38821D7C for ; Fri, 18 Oct 2019 20:04:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6D38821D7C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 46vxnf5x7gzDqhn for ; Sat, 19 Oct 2019 07:04:22 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=permerror (SPF Permanent Error: Unknown mechanism found: ip:192.40.192.88/32) smtp.mailfrom=kernel.crashing.org (client-ip=63.228.1.57; helo=gate.crashing.org; envelope-from=segher@kernel.crashing.org; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 46vxlS1hXVzDqdk for ; Sat, 19 Oct 2019 07:02:28 +1100 (AEDT) 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 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 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Nick Desaulniers , LKML , clang-built-linux , Paul Mackerras , linuxppc-dev Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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