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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7EB0DCF9C71 for ; Tue, 24 Sep 2024 06:39:29 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 11A356B00A8; Tue, 24 Sep 2024 02:39:29 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0CB496B00AA; Tue, 24 Sep 2024 02:39:29 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id ED3FB6B00AB; Tue, 24 Sep 2024 02:39:28 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id CFD3D6B00A8 for ; Tue, 24 Sep 2024 02:39:28 -0400 (EDT) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 7D9C3A15B2 for ; Tue, 24 Sep 2024 06:39:28 +0000 (UTC) X-FDA: 82598680416.04.D403617 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf20.hostedemail.com (Postfix) with ESMTP id 22E3C1C0003 for ; Tue, 24 Sep 2024 06:39:24 +0000 (UTC) Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=mqYapK5m; spf=none (imf20.hostedemail.com: domain of BATV+421eae2cbd7e7788c998+7702+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+421eae2cbd7e7788c998+7702+infradead.org+hch@bombadil.srs.infradead.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1727159906; a=rsa-sha256; cv=none; b=bHJHqxnSp7w7VzBrAZmQBJinCI+sI0WPRanmHZn8s5qwJWBv+S0huBl3CvcAwFO7XqTWmw RisMvQMHELBy/iHBxzKlaF437GLx97xxjk8W9m3bY4qogdUa3l0A/76pD4nrP70ZeGoJfk bklDWhAuUl8394Zl3or0OT7I2ilhOz0= ARC-Authentication-Results: i=1; imf20.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=mqYapK5m; spf=none (imf20.hostedemail.com: domain of BATV+421eae2cbd7e7788c998+7702+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+421eae2cbd7e7788c998+7702+infradead.org+hch@bombadil.srs.infradead.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1727159906; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=/bwp9K2z7oMAUdlrrH8WLgUyutuYE9dnJFxhsyUAv/o=; b=0ZvzLwSqK2/fd1l3Vll1Z2hIeUXYu+CdHE18XB8eeNcqZmLrVSRVXRIqbu1KKcYQ8t8Ws+ YBLDGo/+BSCzoQrakjCNYCxstsFYRJCnIzIYtxRaie/Al1vsWwqDfAgvFiyb9q8WUGPnmE 5GhGyfRG2QfFY3SRprySfNpXo+VR8O0= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=/bwp9K2z7oMAUdlrrH8WLgUyutuYE9dnJFxhsyUAv/o=; b=mqYapK5mnJvthtVuUYKp2l3t85 ni0DzoUkLwdThX++tfM2tKch9RobO1gUlXR0sL75EXRANP5AltdhnKG3WykP+eNIDe8ztqcs+FupU OLBoHRoVpGd7wMtMesLuWutFsVfkAbhxINY3io6hvgrTxbgBhf0OMaPJs44KqDKsH+qYGdG7Cc1Sh INSzs3Q7mJ3pmr34KmPMW3A8Epa5VoHxafiJpRrIp06Sx8kvGcKAIF0Haio6Ry8xQoHc8ytLxDZDS 6kNFaOUb6EKRB5Jrcb4YwZMvxQ3ZX2ZJkuzVZILDy8yyxTWSAFptV6WrUyWM00dUicZekS40G7nOq e1QEp/3w==; Received: from hch by bombadil.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1sszCi-00000001HHO-2wcJ; Tue, 24 Sep 2024 06:39:20 +0000 Date: Mon, 23 Sep 2024 23:39:20 -0700 From: Christoph Hellwig To: Vladimir Kondratiev Cc: Christoph Hellwig , Paul Walmsley , Palmer Dabbelt , Albert Ou , Andrew Morton , "linux-riscv@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" Subject: Re: [PATCH] riscv: make ZONE_DMA32 optional Message-ID: References: <20240827113611.537302-1-vladimir.kondratiev@mobileye.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-Stat-Signature: 33wbpz7q4qz8c6m8j4bx5xztnijzx8tb X-Rspamd-Queue-Id: 22E3C1C0003 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1727159964-453217 X-HE-Meta: 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 YjahBUK5 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun, Sep 22, 2024 at 10:06:59AM +0000, Vladimir Kondratiev wrote: > This is the whole point - there are platforms where you can't allocate 32-bit > dma-able memory. Ugg. They will be broke for all kinds of devices (plug in PCIe devices IP IP blocks). > Unless there's IOMMU or some platform specific tricks, > DMA address is same as physical address. Well, that's where the usual platform specific trick is, as the platforms with high DRAM either have a mapping between physical and DMA range (see the dma_ranges concept in the DMA and OF code) or a mirror of the higher addresses. Or very rarely (e.g. sparc) a required IOMMU that is always used.