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 BC9EBC433F5 for ; Wed, 22 Dec 2021 13:30:40 +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:Cc:To:Subject:Message-ID:Date:From: In-Reply-To:References:MIME-Version:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=J0pyymWcsTWuvWfsEuVuvZ+2PqnWgS7VhSRyFpCSnJM=; b=ljfymP5T7NKuiP D+w9t4HwiToVXG6IZ/NAUq9Yga4rKXqsUGk2MCLM/2/1m1zHBhWuXZBDIIqzfu+5kznl5z0cc4WiS DA0P+CcTACEsVTTdqct00e+XTJG2xVNX9kvMM6KmfvyqJR4aCtxPUsBgkkUX0cCRqI0OFwW5iuE3R PPbFT1ol7mQLXhVvRTVRPiob0gvC+OIJeTiYKTvVnUbUX1iwzplxiej0WTZ3S861+K50r9PI0so3+ bjTKOXYGZdX3dTlcM67RGBO6NODcFeFMBFzQkKQZ7Nb4kAtHTrwqitEYvCDwQzBHrU7sxmGxP1uS7 /xIaC95vP8wIFHzrZ2qw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1n01hP-00AXmF-Pd; Wed, 22 Dec 2021 13:30:31 +0000 Received: from mout.kundenserver.de ([217.72.192.74]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1n01gT-00AXJN-5w for linux-riscv@lists.infradead.org; Wed, 22 Dec 2021 13:29:37 +0000 Received: from mail-wr1-f45.google.com ([209.85.221.45]) by mrelayeu.kundenserver.de (mreue108 [213.165.67.113]) with ESMTPSA (Nemesis) id 1MA7Om-1nAR0516PC-00BbFU for ; Wed, 22 Dec 2021 14:29:31 +0100 Received: by mail-wr1-f45.google.com with SMTP id t26so4949354wrb.4 for ; Wed, 22 Dec 2021 05:29:31 -0800 (PST) X-Gm-Message-State: AOAM5303mi2+yTNPLhOdQzwIpTTA8SE1y1EmJJf0NTxjtvGFrX0X5/fj H5lND9kn0tvF20JYsv0+EtQT+UpFc2qKNijwdpU= X-Google-Smtp-Source: ABdhPJw0nfzYEJHZ07y3vp99CtMxCtIx4hPphKIiW8tqqMsfij+vBR7u+JaOTSFOhAqaTYEbtHQeGItEWv0smRfi5/Y= X-Received: by 2002:a5d:484f:: with SMTP id n15mr2115267wrs.219.1640179770964; Wed, 22 Dec 2021 05:29:30 -0800 (PST) MIME-Version: 1.0 References: <20211221163532.2636028-1-guoren@kernel.org> In-Reply-To: From: Arnd Bergmann Date: Wed, 22 Dec 2021 14:29:14 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 00/13] riscv: compat: Add COMPAT mode support for rv64 To: Guo Ren Cc: Arnd Bergmann , Palmer Dabbelt , Anup Patel , gregkh , liush , Wei Fu , Drew Fustini , Wang Junqiang , =?UTF-8?B?V2VpIFd1ICjlkLTkvJ8p?= , Linux Kernel Mailing List , linux-riscv , linux-csky@vger.kernel.org, Guo Ren X-Provags-ID: V03:K1:Yx1sCrnTBUqhZncC+oVU+U/GJxG9IqaJNy7D9KmPUROdoKqKS81 R46OQgAHBStvvLujbSHq+dy4i8d14Tkr7D9VAxny7MYjDqIBD778nc98OoXrqE1mR8xVtJW M29W0fPkGVRhr4MhIiPQtB2cmE3daEnV8G2IG9kyu8OjoJZbUZcbeu3g8rpKEraz7dvZM5H /q6MNpDKf7uIUnEUeAH/A== X-UI-Out-Filterresults: notjunk:1;V03:K0:pp3XHnKKmkY=:IDHmTQx5HqkyiXBuA5RQHX bZquvR3hGx00DUna37hZvdGYGQ8knlj1G+RNOlzKUpq/pWDQ48f0moORXb6dTO7UCdtSV6Q1o /GJwktbMkZZuJDpknM+sWj/b3YlrBffRE3d/Nyw1BZsY/wdGmNtrDw+DfcxqzrgWPKTw2bFzM rXeqLVMaTkJRVxaWZW4otUQuytZ+1ThhgBasHDVRn/rCMahGO4toT64V+yudqzEFVsaLmCkOF 8zIm0mAnVG2cnMZ5QevUabvuIL+Mku6StovKWgmWfAnPJ7WjrVWyWA++DasNiALb3znQlJIC8 +7ZqvOHdb5Omx/ncOrQ7rfmvEQsCg1Ee5peYltTs6MJankdYxeeAb4Lrh1gfQRzA7BMfNCR89 8TnqVgdRIllDqEIRdKqio8xNadqhQS8tN1MrmjI4lbw4hp4nIIuUy62s77nMRpxoxMs8Am1kI cp0/7t6Irc4C7ygreUXlX+lLAzk6VIKAHz5LiLZvBnaD+8ibQKuseDvf1GHXycNbdQ0e5muRi Ah2PgZEDbFHndbTvu7ebsOjwAVI291TDUAHAfuF1Ov+mCYElL58J+VwK1jYQm6MBYyhbtCmyK +/2WYKH761ninvFONlzVwSw/sPrDKRaqLMqLN22+vs7eisRvP5ioK1wHNu2tm6h9w6LWVYQSS 6LnX1+Uw8bojcrSp5u9DjPGan7mW2T+U+EbXmdGJMBztjuOQJqKx76Hw92uTmkkHwV5NwNhvn l7IdT2zG41euHq/b1KkvuysfJACzXGwt/0we0f3urgoMfLBXU1rT9YchNhUpH3ndYgk3bQP14 a2c/Dn917yorydUFuIGGQLnA+Pa7rkmWREKku09EBHitG0pkH0= X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211222_052933_554671_5FB61AC4 X-CRM114-Status: GOOD ( 19.21 ) X-BeenThere: linux-riscv@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-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Wed, Dec 22, 2021 at 1:59 PM Guo Ren wrote: > On Wed, Dec 22, 2021 at 2:10 AM Arnd Bergmann wrote: > > On Tue, Dec 21, 2021 at 5:35 PM wrote: > > > There is still some benefit in b), but it would need to be weighed > > against the downsides above. Can you explain in more detail what > > use cases you have in mind, and which CPU cores actually support > > this mode? > The most reason is about b), see our customer's product: > https://www.cnx-software.com/2021/10/25/allwinner-d1s-f133-risc-v-processor-64mb-ddr2/ > > So I think all our next generation rv64 cores should support > compat-mode. Compare to releasing rv32-full core, rv64 compat-mode is > very cheap for our CPU design. > > You would get the answer when our new generation CPU is announced and it's soon. > > Currently, only qemu supports rv64 compact mode, that is my colleague > (LIU Zhi Wei) contributed. Right, that does make a lot of sense. I'm not sure we'll see a lot more of 64MB DDR2 SiP implementations when a 128MB or even 256MB DDR3 configuration has almost the same cost, but for any of those sizes I can see why you'd want to run 32-bit user space, as well as 64-bit kernels. Arnd _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv