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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,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 4706BC3A5A5 for ; Tue, 3 Sep 2019 05:21:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1D7E021897 for ; Tue, 3 Sep 2019 05:21:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=c-s.fr header.i=@c-s.fr header.b="jBFEMAcM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726180AbfICFVy (ORCPT ); Tue, 3 Sep 2019 01:21:54 -0400 Received: from pegase1.c-s.fr ([93.17.236.30]:10698 "EHLO pegase1.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725895AbfICFVy (ORCPT ); Tue, 3 Sep 2019 01:21:54 -0400 Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 46MwL728ttz9vBn0; Tue, 3 Sep 2019 07:21:51 +0200 (CEST) Authentication-Results: localhost; dkim=pass reason="1024-bit key; insecure key" header.d=c-s.fr header.i=@c-s.fr header.b=jBFEMAcM; dkim-adsp=pass; dkim-atps=neutral X-Virus-Scanned: Debian amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [192.168.12.234]) (amavisd-new, port 10024) with ESMTP id z_oZM-nQGOxo; Tue, 3 Sep 2019 07:21:51 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 46MwL70zsbz9vBmy; Tue, 3 Sep 2019 07:21:51 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=c-s.fr; s=mail; t=1567488111; bh=qbuG+RUrs+H+R7AEWaZZdUx62SA2ZhQIuC96dqC+GUI=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=jBFEMAcMs2AHYbs/GpdtbDn7S1VrRGQBB7YEJw9TsnpRgS+AtzCpbQ4eSe3jBkhyx Mn/CKCwsDWhlgbLSe0Os7Zs5OnqddxZHdmZB+flZnhK/DFByF7d29SbMSGfWBzi78Y 2iEoMt5mUBcFzMS+fAwFb5fuF9OciRdNJ3irQjxA= Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id E63A58B79F; Tue, 3 Sep 2019 07:21:51 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id sB_vCzEfMRgO; Tue, 3 Sep 2019 07:21:51 +0200 (CEST) Received: from localhost.localdomain (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 213A08B761; Tue, 3 Sep 2019 07:21:50 +0200 (CEST) Subject: Re: [PATCH v7 5/6] powerpc/64: Make COMPAT user-selectable disabled on littleendian by default. To: Michael Ellerman , Segher Boessenkool Cc: Michal Suchanek , linuxppc-dev@lists.ozlabs.org, Benjamin Herrenschmidt , Paul Mackerras , Alexander Viro , Nicholas Piggin , Breno Leitao , Arnd Bergmann , Heiko Carstens , Greg Kroah-Hartman , Firoz Khan , Thomas Gleixner , Joel Stanley , Hari Bathini , Michael Neuling , Andrew Donnellan , Russell Currey , Diana Craciun , "Eric W. Biederman" , David Hildenbrand , Allison Randal , Andrew Morton , Madhavan Srinivasan , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org References: <87ftlftpy7.fsf@mpe.ellerman.id.au> <20190902130008.GZ31406@gate.crashing.org> <87k1aqs19n.fsf@mpe.ellerman.id.au> From: Christophe Leroy Message-ID: <296c9fce-f38c-cc53-4c1e-306c4dec17bc@c-s.fr> Date: Tue, 3 Sep 2019 05:21:49 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <87k1aqs19n.fsf@mpe.ellerman.id.au> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 09/02/2019 11:53 PM, Michael Ellerman wrote: > Segher Boessenkool writes: >> On Mon, Sep 02, 2019 at 12:03:12PM +1000, Michael Ellerman wrote: >>> Michal Suchanek writes: >>>> On bigendian ppc64 it is common to have 32bit legacy binaries but much >>>> less so on littleendian. >>> >>> I think the toolchain people will tell you that there is no 32-bit >>> little endian ABI defined at all, if anything works it's by accident. > ^ > v2 > >> There of course is a lot of powerpcle-* support. The ABI used for it >> on linux is the SYSV ABI, just like on BE 32-bit. > > I was talking about ELFv2, which is 64-bit only. But that was based on > me thinking we had a hard assumption in the kernel that ppc64le kernels > always expect ELFv2 userland. Looking at the code though I was wrong > about that, it looks like we will run little endian ELFv1 binaries, > though I don't think anyone is testing it. > >> There also is specific powerpcle-linux support in GCC, and in binutils, >> too. Also, config.guess/config.sub supports it. Half a year ago this >> all built fine (no, I don't test it often either). >> >> I don't think glibc supports it though, so I wonder if anyone builds an >> actual system with it? Maybe busybox or the like? >> >>> So I think we should not make this selectable, unless someone puts their >>> hand up to say they want it and are willing to test it and keep it >>> working. >> >> What about actual 32-bit LE systems? Does anyone still use those? > > Not that I've ever heard of. > We dropped support from 32-bit LE at least with a1f3ae3fe8a1 ("powerpc/32: Use stmw/lmw for registers save/restore in asm"). Discussion about it can be found at https://patchwork.ozlabs.org/patch/899465/ Christophe