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 A0B0BC64ED8 for ; Mon, 27 Feb 2023 15:51:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:CC:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=GwQVFi+MOKP7OeTg6DU1rOU5pM5GUEcYs67D8swXL7g=; b=WqgcLYvxco93l5 X9YXQEmFZRKPKzsK5i7zahTr9xcPsf19CSIiJhZN3Gd3MrQdNqYrpZ0aXo+QBS0fYUcaAU3I8lOj+ CQklxUBL5r4gqVg4eA1JmKTQbEC96gcgnH744hBXncBOX0MBR4qKaCJlaVOaQ5DmBQqzfp5cdMoh/ xW21ex4kmFkXWKP5ocMdwUbMA6ejZI24jGiGh6bW8o6qd86icWODRzOTWc8igtSxPeGSI1eeX4t8P hSvvW/oJP88sXXLLwLJTtimV9odMU6X9YHkYFIwQMtCB+bGgmd2fSLOJL3IeicIautdgNbQU0Z8+J dvGo8IIiiws9M+6l8/kg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1pWfmR-00AFc5-Vi; Mon, 27 Feb 2023 15:51:12 +0000 Received: from mx.sberdevices.ru ([45.89.227.171]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1pWfmO-00AFaB-6J; Mon, 27 Feb 2023 15:51:10 +0000 Received: from s-lin-edge02.sberdevices.ru (localhost [127.0.0.1]) by mx.sberdevices.ru (Postfix) with ESMTP id 429E55FD19; Mon, 27 Feb 2023 18:51:01 +0300 (MSK) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sberdevices.ru; s=mail; t=1677513061; bh=3NB9Zg77s2V7JybNtvo3+pUvISAkjx2ar52mHE6m9LM=; h=Date:From:To:Subject:Message-ID:MIME-Version:Content-Type; b=aisrcImdj/tfvNXRxaJn1zZcbN69p/PRhiu3yzK8Tze0Mz/BmWPD0ZWvAVz+5hTq7 UqDGSF6wO1yM9MeQ1P9sO7eD4mI3QSt/FteDeQRZLWkCLdGL24qF4OVyGW2Rm0MtkA cwBuyO8phnRG+Ai2e2BxAh1IjNDU1lAkf7Yj/7OxAsKwJX2cq1v62610SjR52W71JD hQmSthvuH3J8Flsr7n622cZcgehMj9jRpktsDzJrYKg5h8cmnA8IT4PGPoSnrXUcI+ 0P88nnY7yxN+o8KQIT+vcOc16XbxdFsaZym8rN8oX0XQRjDBWUzUPkdWg8DOsM2io0 KkWfQuYVkSE5w== Received: from S-MS-EXCH01.sberdevices.ru (S-MS-EXCH01.sberdevices.ru [172.16.1.4]) by mx.sberdevices.ru (Postfix) with ESMTP; Mon, 27 Feb 2023 18:51:00 +0300 (MSK) Date: Mon, 27 Feb 2023 18:51:00 +0300 From: Dmitry Rokosov To: Arnd Bergmann CC: Neil Armstrong , Alexey Romanov , Rob Herring , , Kevin Hilman , , , Linus Walleij , , , , , Subject: Re: [PATCH v1 0/3] Meson A1 32-bit support Message-ID: <20230227155100.hhl4yvkyfqfyoa6h@CAB-WSD-L081021> References: <20230222115020.55867-1-avromanov@sberdevices.ru> <8e5f9bfa-d612-cd43-d722-d04c40938c62@linaro.org> <20230227142809.kujmrraf3pcdhqyn@CAB-WSD-L081021> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20220415 X-Originating-IP: [172.16.1.6] X-ClientProxiedBy: S-MS-EXCH02.sberdevices.ru (172.16.1.5) To S-MS-EXCH01.sberdevices.ru (172.16.1.4) X-KSMG-Rule-ID: 4 X-KSMG-Message-Action: clean X-KSMG-AntiSpam-Status: not scanned, disabled by settings X-KSMG-AntiSpam-Interceptor-Info: not scanned X-KSMG-AntiPhishing: not scanned, disabled by settings X-KSMG-AntiVirus: Kaspersky Secure Mail Gateway, version 1.1.2.30, bases: 2023/02/27 12:14:00 #20900843 X-KSMG-AntiVirus-Status: Clean, skipped X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230227_075108_602542_788ABD08 X-CRM114-Status: GOOD ( 27.93 ) X-BeenThere: linux-amlogic@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-amlogic" Errors-To: linux-amlogic-bounces+linux-amlogic=archiver.kernel.org@lists.infradead.org Hello Arnd, On Mon, Feb 27, 2023 at 03:58:50PM +0100, Arnd Bergmann wrote: > On Mon, Feb 27, 2023, at 15:28, Dmitry Rokosov wrote: > > Hello Neil! > > > > On Mon, Feb 27, 2023 at 09:15:04AM +0100, neil.armstrong@linaro.org wrote: > > > > [...] > > > >> I'm aware Amlogic also runs their kernel as 32bit to gain a few kbytes > >> of memory, but those processors are ARMv8 and the arm64 arch code > >> has been designed for those CPUs. > >> > >> So far I didn't find a single good reason to add 32bit support for > >> ARMv8 Amlogic based SoCs, if you have a solid reason please share. > > > > I totally agree with you, but I suppose it's fully related to 'big' > > Amlogic SoC like S905_ or A311_ series. A113L (aka 'a1') is > > a cost-efficient dual-core SoC which is used for small, cheap solutions > > with cheap components. Every cent is important during BoM development. > > That's why usually ODMs install small ROM and RAM capacity, and each > > megabyte is important for RAM/ROM kernel and rootfs footprints. > > Why am I talking about rootfs? For such small projects a good > > choice is buildroot rootfs assembling framework. Unfortunatelly, > > buildroot doesn't support 'compat' mode when kernel and userspace have > > a different bitness. In the internal project, we save several > > percents of ROM/RAM free space using 32-bit configuration (mostly rootfs > > ROM space, to be honest). Therefore, for such 'little' cost-efficient > > SoCs we can make an exception and support 32-bit configuration, from my > > point of view. > > > > What do you think about that? > > I would argue that is a problem with buildroot, and using a 32-bit > kernel is not something we should encourage over fixing buildroot > to do it right, or building the kernel separately from the rootfs. > > We do allow building support for a couple of ARMv8 SoCs in 32-bit > mode, but that is usually because they ship with a 32-bit bootrom > and cannot actually run a 64-bit kernel. To be honest, I didn't know about this principle. It looks like a very rational approach "start from max supported bitness". Based on overall maintainers opinion, we have to prepare a patch for buildroot to support compat mode :) [...] -- Thank you, Dmitry _______________________________________________ linux-amlogic mailing list linux-amlogic@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-amlogic