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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 83370CAC5B8 for ; Sat, 27 Sep 2025 01:45:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:MIME-Version:Date:Message-ID:From:References:CC:To: Subject:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=u9nZYSwsMGPvkMj1b62UHiMQVnCSrOBHGMlnTb9xAkc=; b=WEBDN8+gKkv261iI8JzZYQmzV2 Ogh3rq13fDLIgmbI/LUUadqbfOYh4o8cruXXdUNGXk2a2k2r7Z0renNbGBXfVcCAdIo8OcQ4YcU4H KVJIaqXm7vR3z0DHATSfA1d2S53g58MlaCgC2nv59Gm3W5dNLdRWxvVupkcgnHMFYOTSiUcU6eQ2A jsG8Alik8oarV/wbMrTwLlN7gPYN/vA2BJSsMncetre2BVKqm0Kmz+bSODWiq4AsamA3dyYmVL7tj foRmHhRQ65KkCRVl22ds/41kyQguyRVTse3AjrRR7i1U4TlOps5TvFJThk3KJSXE3tHhl7ywlAcoQ n3iGkuaw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1v2Jzo-0000000682B-27yv; Sat, 27 Sep 2025 01:45:08 +0000 Received: from szxga01-in.huawei.com ([45.249.212.187]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1v2Jzk-000000067s5-1VRy for linux-arm-kernel@lists.infradead.org; Sat, 27 Sep 2025 01:45:06 +0000 Received: from mail.maildlp.com (unknown [172.19.163.48]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4cYVX05stfz13L4p; Sat, 27 Sep 2025 09:40:32 +0800 (CST) Received: from dggpemf500002.china.huawei.com (unknown [7.185.36.57]) by mail.maildlp.com (Postfix) with ESMTPS id 4B6AF18006C; Sat, 27 Sep 2025 09:44:55 +0800 (CST) Received: from [10.174.178.247] (10.174.178.247) by dggpemf500002.china.huawei.com (7.185.36.57) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Sat, 27 Sep 2025 09:44:54 +0800 Subject: Re: [PATCH] arm64: Kconfig: Make CPU_BIG_ENDIAN depend on BROKEN To: Will Deacon , CC: Catalin Marinas , Marc Zyngier , Ard Biesheuvel , Arnd Bergmann , Jonathan Cameron , Guenter Roeck References: <20250919184025.15416-1-will@kernel.org> From: Hanjun Guo Message-ID: <488c37c6-fea3-8726-3a16-b042ed45609d@huawei.com> Date: Sat, 27 Sep 2025 09:44:53 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20250919184025.15416-1-will@kernel.org> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.178.247] X-ClientProxiedBy: kwepems500002.china.huawei.com (7.221.188.17) To dggpemf500002.china.huawei.com (7.185.36.57) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250926_184504_559551_F4B4FBF7 X-CRM114-Status: GOOD ( 16.18 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Will, On 2025/9/20 2:40, Will Deacon wrote: > Big-endian arm64 configurations are vanishingly rare, yet we still claim > to support them in Linux despite very limited testing or visible > interest. Supporting big-endian adds unnecessary burden to reviewers and > contributors which, without any known active users, is hard to justify. > For example, recent work to improve our futex routines and to implement > nested virtualisation support is non-trivially complicated by having to > support both big- and little-endianness. > > Back in 2019 [1], it was claimed that Huawei were using arm64 big-endian > machines in their telecommunication products but I don't know whether > that's still the case and certainly haven't seen any patch contributions > to help support or maintain it. > > Make CPU_BIG_ENDIAN depend on BROKEN as an initial deprecation step > towards its removal. > > Cc: Catalin Marinas > Cc: Marc Zyngier > Cc: Ard Biesheuvel > Cc: Arnd Bergmann > Cc: Hanjun Guo > Cc: Jonathan Cameron > Cc: Guenter Roeck > Link: https://lore.kernel.org/linux-arm-kernel/73701e9f-bee1-7ae8-2277-7a3576171cd4@huawei.com/ [1] > Signed-off-by: Will Deacon > --- > > Cc'ing Guenter as a heads-up in case he needs to turn down his testing > to avoid this causing a false regression report. > > Cc'ing Hanjun and Jonathan for clarity on the telecommunication > situation. Sorry for the late reply, the current products are still using the ARM64 big-endian architecture on Linux, but the future evolution will not. It will take quite a while (for years) for the end of the product life cycle, please keep it as BROKEN. Thanks Hanjun