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=-2.5 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, T_DKIMWL_WL_HIGH,URIBL_BLOCKED,USER_AGENT_MUTT 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 7F38FC28D1B for ; Thu, 6 Jun 2019 07:08:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 55B9420872 for ; Thu, 6 Jun 2019 07:08:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559804891; bh=sOq1aIPwoGF1dlKwf8g6qXJnPdLXODwo9qjIaiPRjr4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=Tb8ZhSetqcXOkAZ+1Rte9QSt9uHgsYTo70S7XCJxyj6i5mSW1wiWorGpn8BUH4e+S BPlkKQr36CUQxiA0CwxiqW8AMiGP+DY7NP7/pDZdM6K+8qHZQklynCPQ6DHWT1w1JH cInt5e7bEEK7vLttK811zgXzzjuGcV6qcE/rtnvs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726157AbfFFHIK (ORCPT ); Thu, 6 Jun 2019 03:08:10 -0400 Received: from mail.kernel.org ([198.145.29.99]:43036 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725782AbfFFHIK (ORCPT ); Thu, 6 Jun 2019 03:08:10 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B3CDA2083D; Thu, 6 Jun 2019 07:08:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559804889; bh=sOq1aIPwoGF1dlKwf8g6qXJnPdLXODwo9qjIaiPRjr4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=VmXsfdmVy+fYk40zwh0ypfxRSF+bHgzmqyKHAiM+pwFTnrkAYrmCy4z6OTf5t0zFp +i6i3PMpxynsI4LQIarHQz/erzaloaH+NgO6vu4I8GL0Ug4OinVxnYitknMlGd1KDv 5OIG5iFXvxUcXdZFqCU1PpD43K9Fp16HZ8wVeVgo= Date: Thu, 6 Jun 2019 09:08:07 +0200 From: Greg KH To: Ard Biesheuvel Cc: Nick Desaulniers , Rolf Eike Beer , Linus Torvalds , Matt Fleming , Peter Zijlstra , Thomas Gleixner , linux-efi , Linux Kernel Developers List , stable , clang-built-linux Subject: Re: Building arm64 EFI stub with -fpie breaks build of 4.9.x (undefined reference to `__efistub__GLOBAL_OFFSET_TABLE_') Message-ID: <20190606070807.GA17985@kroah.com> References: <779905244.a0lJJiZRjM@devpool35> <20190605162626.GA31164@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.0 (2019-05-25) Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Thu, Jun 06, 2019 at 08:55:29AM +0200, Ard Biesheuvel wrote: > On Wed, 5 Jun 2019 at 22:48, Nick Desaulniers wrote: > > > > On Wed, Jun 5, 2019 at 11:42 AM Ard Biesheuvel > > wrote: > > > For the record, this is an example of why I think backporting those > > > clang enablement patches is a bad idea. > > > > There's always a risk involved with backports of any kind; more CI > > coverage can help us mitigate some of these risks in an automated > > fashion before we get user reports like this. I meet with the > > KernelCI folks weekly, so I'll double check on the coverage of the > > stable tree's branches. The 0day folks are also very responsive and > > I've spoken with them a few times, so I'll try to get to the bottom of > > why this wasn't reported by either of those. > > > > Also, these patches help keep Android, CrOS, and Google internal > > production kernels closer to their upstream sources. > > > > > We can't actually build those > > > kernels with clang, can we? So what is the point? > > > > Here's last night's build: > > https://travis-ci.com/ClangBuiltLinux/continuous-integration/builds/114388434 > > > > If you are saying that plain upstream 4.9-stable defconfig can be > built with Clang, then I am pleasantly surprised. I know some specific configs can, there's no rule that I know of that 'defconfig' support is required. But then again, it might also work, try it and see :) > > Also, Android and CrOS have shipped X million devices w/ 4.9 kernels > > built with Clang. I think this number will grow at least one order of > > magnitude imminently. > > > > I know that (since you keep reminding me :-)), but obviously, Google > does not care about changes that regress GCC support. What are you talking about? Bugs happen all the time, what specifically did "Google" do to break gcc support? If you are referring to this patch, and it is a regression, of course I will revert it. But note that gcc and 4.9 works just fine for all of the other users right now, remember we do do a lot of testing of these releases. thanks, greg k-h