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 65EC9C78849 for ; Fri, 20 Sep 2024 14:04:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id BCC536B0085; Fri, 20 Sep 2024 10:04:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B7B396B0088; Fri, 20 Sep 2024 10:04:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A6A5A6B0089; Fri, 20 Sep 2024 10:04:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 887416B0085 for ; Fri, 20 Sep 2024 10:04:16 -0400 (EDT) Received: from smtpin02.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id A9D6D160412 for ; Fri, 20 Sep 2024 14:04:15 +0000 (UTC) X-FDA: 82585286070.02.9CBBF13 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf25.hostedemail.com (Postfix) with ESMTP id 5ACB5A0019 for ; Fri, 20 Sep 2024 14:04:12 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=RnEP+KJJ; spf=none (imf25.hostedemail.com: domain of BATV+6ff2ccedb5c7e3cd0239+7698+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+6ff2ccedb5c7e3cd0239+7698+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=1726840939; 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=RCwlKLEJXQ81sm67JF7/OQA8EjktrgnBwq8TDvkYkrU=; b=FdAUkexidIILzpkgGOlAaUR0mAyw2O3+h/Xxvd9BFG6Z80KTAKn4iAOQJW4xclcSRIuVK0 izuKjV4c8rE0H86UKkLAGN7BKvpuhYQ9OU9yPYHk8xkzk1J8qlt5B8bEh/P2bNbjGc8o/Q urN6LBB6ma7Jtnv10xpjdH+vdLn1YZc= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1726840939; a=rsa-sha256; cv=none; b=VvJkFkBUIf8col0jS3H4csR3kqBixjCJF7y6D/YYe91V74Tr7kUu+4oM0D02roz5IXFNL/ BFlEPlHnZqrbska4XNniFAHmLZEMays8SDvRGnp4RIx3kHndofTALHkQUwuRqGB2vE966H VEn5Ce7KKlo8M1GJi5q+lUmwVVEOGa8= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=RnEP+KJJ; spf=none (imf25.hostedemail.com: domain of BATV+6ff2ccedb5c7e3cd0239+7698+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+6ff2ccedb5c7e3cd0239+7698+infradead.org+hch@bombadil.srs.infradead.org; dmarc=none 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=RCwlKLEJXQ81sm67JF7/OQA8EjktrgnBwq8TDvkYkrU=; b=RnEP+KJJVour4Wz2TFpMO2awow dciUCqYfTUUpPqPx7hl88uS9bw0ASNFt/qia735KVxZWkE6iY7UcFeRxg2MMbWigSzKi2JVQN8ser GXOrClbTLj1jU6mwSBmyI85Ix8U6HXDjNV9Sac0L9HZ4DqIOcDp/Xi6hp/cHch1wbHeGpcfQtFDOJ gC/8LOnfu7Idg1caicV3Atx0ieiH08dgd9cA8aKgu3NDjItfoL3Ij50BjqaejBPnRwekqSSIWQjNa +qWNox54k/NzEOmU9ohjHe8/UaBk2gxFT3rpO/vowzS4gGzDH/ate3NT0aekeLh1A4e2pMBD3ozJE yWdDL9zw==; Received: from hch by bombadil.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1sreEw-0000000CK7O-25DY; Fri, 20 Sep 2024 14:04:06 +0000 Date: Fri, 20 Sep 2024 07:04:06 -0700 From: Christoph Hellwig To: Vladimir Kondratiev Cc: 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: <20240827113611.537302-1-vladimir.kondratiev@mobileye.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-Stat-Signature: i8aap8od4jf7i8rbygaenb6ed7eob6x5 X-Rspamd-Queue-Id: 5ACB5A0019 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1726841052-22904 X-HE-Meta: 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 8VCYpnKO 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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 Tue, Aug 27, 2024 at 02:36:11PM +0300, Vladimir Kondratiev wrote: > It is not necessary any RISCV platform has ZONE_DMA32. That is an odd statement. The point of ZONE_DMA32 is to make sure that drivers can always allocate 32-bit DMAable memory, and without ZONE_DMA32 that is very hard to provide unless you always have an IOMMU. > Example - if platform has no DRAM in [0..4G] region, > it will report failure like below each boot. ZONE_DMA32 is supposed to contain the 32-bit dma addressable memory, not 32-bit physical. Take a look at the changes that just went into Linus' tree for that.