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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,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 5DE5DC32750 for ; Fri, 2 Aug 2019 08:44:56 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 36EFA2073D for ; Fri, 2 Aug 2019 08:44:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="F8QXWyqy" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 36EFA2073D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-riscv-bounces+infradead-linux-riscv=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject: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=mXFgU4GiOS4GDBo3f1s1HbWKVKAVY8VFwl+8sV/NacI=; b=F8QXWyqy+Bip0I pt9VeHSfJsGY8AQupeNA5ioiHqlUbitgJrlWG077BdZWSi7AP9lLR0xXYVIlVppDzpXvPJCsSK1KK obmFQh2bgUb7BxfJd7AinPVUWspLW/K6stsy1qHXMKEo0VU+jB7sDjDeadkJlz6UQplEBZAsqQ2Ie Ss+4i93jB0EMI8Md1JFNBFZirNgpr+CFq693VhSRmf06ptNSAjtWNqj+ov5AL820/DF46+8Fiitu+ uFVL1DUL9KeDthQ5QM3AA2B6o8Bhh4kM9EsLgTLLHCW7EcYcGc6+utN/u0a2K66XU7vInRo0JhM4a Ud+h/zGcBj6JTBEXx+xA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1htTBH-0000mg-7R; Fri, 02 Aug 2019 08:44:55 +0000 Received: from hch by bombadil.infradead.org with local (Exim 4.92 #3 (Red Hat Linux)) id 1htTBF-0000mV-5w; Fri, 02 Aug 2019 08:44:53 +0000 Date: Fri, 2 Aug 2019 01:44:53 -0700 From: Christoph Hellwig To: Paul Walmsley Subject: Re: [PATCH] riscv: kbuild: add virtual memory system selection Message-ID: <20190802084453.GA1410@infradead.org> References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.4 (2019-03-13) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Alexandre Ghiti Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+infradead-linux-riscv=archiver.kernel.org@lists.infradead.org On Fri, Jul 26, 2019 at 01:00:49PM -0700, Paul Walmsley wrote: > > The RISC-V specifications currently define three virtual memory > translation systems: Sv32, Sv39, and Sv48. Sv32 is currently specific > to 32-bit systems; Sv39 and Sv48 are currently specific to 64-bit > systems. The current kernel only supports Sv32 and Sv39, but we'd > like to start preparing for Sv48. As an initial step, allow the > virtual memory translation system to be selected via kbuild, and stop > the build if an option is selected that the kernel doen't currently > support. > > This patch currently has no functional impact. It cause the user to be able to select a config which thus won't build. So it is not just useless, which already is a reason not to merge it, but actively harmful, which is even worse. Even if we assume we want to implement Sv48 eventually (which seems to be a bit off), we need to make this a runtime choice and not a compile time one to not balloon the number of configs that distributions (and kernel developers) need to support. _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv