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=-7.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 CF72CC4320E for ; Thu, 26 Aug 2021 04:55:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B5E4E6103C for ; Thu, 26 Aug 2021 04:55:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238098AbhHZE4k (ORCPT ); Thu, 26 Aug 2021 00:56:40 -0400 Received: from pegase2.c-s.fr ([93.17.235.10]:47249 "EHLO pegase2.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229566AbhHZE4j (ORCPT ); Thu, 26 Aug 2021 00:56:39 -0400 Received: from localhost (mailhub3.si.c-s.fr [172.26.127.67]) by localhost (Postfix) with ESMTP id 4Gw9XR4Bclz9sV0; Thu, 26 Aug 2021 06:55:51 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from pegase2.c-s.fr ([172.26.127.65]) by localhost (pegase2.c-s.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id wXGpXvuB0tMJ; Thu, 26 Aug 2021 06:55:51 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase2.c-s.fr (Postfix) with ESMTP id 4Gw9XR333yz9sTw; Thu, 26 Aug 2021 06:55:51 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 444C88B875; Thu, 26 Aug 2021 06:55:51 +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 xTJD91pQL4sF; Thu, 26 Aug 2021 06:55:51 +0200 (CEST) Received: from [192.168.4.90] (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id E11DD8B774; Thu, 26 Aug 2021 06:55:50 +0200 (CEST) Subject: Re: [PATCH] powerpc: Make set_endian() return EINVAL when not supporting little endian To: Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org References: <87bl5kc1os.fsf@mpe.ellerman.id.au> From: Christophe Leroy Message-ID: Date: Thu, 26 Aug 2021 06:55:49 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <87bl5kc1os.fsf@mpe.ellerman.id.au> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le 26/08/2021 à 05:41, Michael Ellerman a écrit : > Christophe Leroy writes: >> There is no point in modifying MSR_LE bit on CPUs not supporting >> little endian. > > Isn't that an ABI break? Or an ABI fix ? I don't know. My first thought was that all other 32 bits architectures were returning -EINVAL, but looking at the man page of prctl, it is explicit that this is powerpc only. > > set_endian(PR_ENDIAN_BIG) should work on a big endian CPU, even if it > does nothing useful. Fair enough. But shouldn't in that case get_endian() return PR_ENDIAN_BIG instead of returning EINVAL ? We can do one or the other, but I think it should at least be consistant between them, shouldn't it ? Christophe