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=-11.4 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL 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 40299C433DF for ; Tue, 18 Aug 2020 19:35:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0DDED206B5 for ; Tue, 18 Aug 2020 19:35:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="fBeobjx2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726684AbgHRTfY (ORCPT ); Tue, 18 Aug 2020 15:35:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43900 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726632AbgHRTfW (ORCPT ); Tue, 18 Aug 2020 15:35:22 -0400 Received: from mail-pf1-x443.google.com (mail-pf1-x443.google.com [IPv6:2607:f8b0:4864:20::443]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 67DDBC061342 for ; Tue, 18 Aug 2020 12:35:22 -0700 (PDT) Received: by mail-pf1-x443.google.com with SMTP id x25so10475437pff.4 for ; Tue, 18 Aug 2020 12:35:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=u9n/mt8PXTBKmKuG3o+opVNeX/HejppKa6InUAJeA7Y=; b=fBeobjx20ZvqgMFkaNVq/ELQ1v5ovZ0pyk/PpsBmxpi2EOtH/EHH8lueVPAsHLePxq YDawcnBGnH+daZxg1HfI4B8CtdqRIK/gYql0D3xoQ0TUhfRELDBak23SSWlBBE4LbVjM GOcdv6i+CQyzRwJ8cpK17uf4nYxuLU6W0cMliF4pcpfMawc+sGUahhJuln49rIcQqoHm OSxljVm9vdqfUgJmt4mCJKFsl9lTEDSfZgznOdmKH74aSCTe9uYNY2txxR95Y8g9Wf3o hYgPfBsNJXhBJN8HzVJWdZxcdF4KCntNSoxeabAYJ+OODBWch4MTEyN02YpX5m3Otqjx 1jiQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=u9n/mt8PXTBKmKuG3o+opVNeX/HejppKa6InUAJeA7Y=; b=l3mt0BHgrd0v/p8cnlava3JB1kqVoF/i/oq4Y8j5B9Xt94DAGSiVfJ+tZIjzqinafY uYKj/Z7FKdUxEG27CTl4hFsW5GyfvEtMnyoa9jNFLtzhLC7iI13mIZSJ5Y9uI0FXGSmy vFhnV7EUXbW+B6kpmBlt9JiI0qicYp+Km4BONYZFhUzksCTjZlgJbMCmYrSGvQYrHWMq xlveiAbbXOMsLDusUnD9/HwejIfm6GmMmGq1SR6ErMW8ZlGwMMgFO4Pvw3osBMtO5+VS zp2iR3WlQxAvnp0uzRWNcCn3quikb3Pxi/f5T7psgVUF9rSf2664433VUx7pNWqoXXAx V8zg== X-Gm-Message-State: AOAM531AH8VWfdmqb13GLU5eVOnPqmdYd6I9ahXJ7dntwKt3QAd4I0BL dfRJz5X193HB//xTxQOoNH3uxgbXhKtBmAr64Uix3A== X-Google-Smtp-Source: ABdhPJwg/txuAGDnuge1cNZ+FrLSNw6Czt9c1sqa0XhG3sA4ynkEYxXs89gPXSKRX1CqOZzs+gt2l8OQKyvMRO6DFvg= X-Received: by 2002:a63:7d8:: with SMTP id 207mr14800708pgh.263.1597779321639; Tue, 18 Aug 2020 12:35:21 -0700 (PDT) MIME-Version: 1.0 References: <20200817220212.338670-1-ndesaulniers@google.com> <76071c24-ec6f-7f7a-4172-082bd574d581@zytor.com> In-Reply-To: <76071c24-ec6f-7f7a-4172-082bd574d581@zytor.com> From: Nick Desaulniers Date: Tue, 18 Aug 2020 12:35:10 -0700 Message-ID: Subject: Re: [PATCH 0/4] -ffreestanding/-fno-builtin-* patches To: "H. Peter Anvin" Cc: Masahiro Yamada , Andrew Morton , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Michal Marek , Linux Kbuild mailing list , LKML , Kees Cook , Tony Luck , Dmitry Vyukov , Michael Ellerman , Joe Perches , Joel Fernandes , Daniel Axtens , Arvind Sankar , Andy Shevchenko , Alexandru Ardelean , Yury Norov , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , Ard Biesheuvel , "Paul E . McKenney" , Daniel Kiper , Bruce Ashfield , Marco Elver , Vamshi K Sthambamkadi , Andi Kleen , Linus Torvalds , =?UTF-8?B?RMOhdmlkIEJvbHZhbnNrw70=?= , Eli Friedman Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 18, 2020 at 12:03 PM H. Peter Anvin wrote: > > I'm not saying "change the semantics", nor am I saying that playing > whack-a-mole *for a limited time* is unreasonable. Ah, ok then. Sorry I mischaracterized your position. > But I would like to go back > to the compiler authors and get them to implement such a #pragma: "this > freestanding implementation *does* support *this specific library function*, > and you are free to call it." I think the first thing that would be helpful is some more detailed write up of the problem statement, and analysis of why the current provided tools are close but not enough. Maybe filing a Clang bug would be helpful to get more feedback from additional toolchain folks than just me (https://bugs.llvm.org/enter_bug.cgi?product=clang "new bug" component). Alternatively, if you're planning on attending plumbers next week, I plan to propose a "kernel toolchain" mailing list for folks with whatever background to discuss future GNU C extensions and how they might be used in kernel development. That might be more appropriate than a Clang bug, but it doesn't exist yet, and feedback might be that it's a terrible idea for some reason. > The only way we can get what we really need from > the compilers is by speaking up and requesting it, and we have done so very > successfully recently; further back we tended to get a lot of > language-lawyering, but these days both the gcc and the clang teams have been > wonderfully responsive. Just trying to avoid the shoe, again. I'd really like to get to the point where we can untangle putting out fires from implementing feature requests though. -- Thanks, ~Nick Desaulniers