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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0AF24CC6B1A for ; Wed, 14 Oct 2026 10:48:01 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C90726B0092; Wed, 14 Oct 2026 06:48:00 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C66E96B0095; Wed, 14 Oct 2026 06:48:00 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B55E16B0096; Wed, 14 Oct 2026 06:48:00 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 911386B0092 for ; Wed, 14 Oct 2026 06:48:00 -0400 (EDT) Received: from smtpin14.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 2CD571A0316 for ; Wed, 14 Oct 2026 10:48:00 +0000 (UTC) X-FDA: 85320906720.14.61BC13A Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf16.hostedemail.com (Postfix) with ESMTP id 4FE5D180003 for ; Wed, 14 Oct 2026 10:47:58 +0000 (UTC) Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=V3c1dj6j; spf=pass (imf16.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1791974878; b=P/vJetwl/dMJYZ4uQYYaEQ0AG736eQjo1reKIdzuhhhFynOAy7EfmHACSJsrla4zJDH3Xa QNMFJPQZi/IOi65EmICegZf0rr9dL3thtbuYEf+BqmMq5hhIHCkZdkcXfu/lTSJlxCcN7l F35T1pvy4OKiNuwgSjz8Iu0zEkDlhjc= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=V3c1dj6j; spf=pass (imf16.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1791974878; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=IApCsci3eSqyBIQ6NmzUaRZb+6TUkOs0tii8wwaDBSI=; b=lXj7qeYd8uDOifKJOnV9jJdep5w7sUOtBH1B+mlfNSRlouKfsu2DcKZSrTdjgEuljYpV8W Wnc40zhwg6vz2LJh3vwZoc4kEmGe0EgAyF8Rm22i2XHmtI51ggHQZvur/KE4nRxGhhsxC7 nOqMu9Q/ej8/HCbPQprsnwxmOrO0EBE= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 3E317407D5; Wed, 14 Oct 2026 10:47:57 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 71E891F000FF; Wed, 14 Oct 2026 10:47:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791974877; bh=IApCsci3eSqyBIQ6NmzUaRZb+6TUkOs0tii8wwaDBSI=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=V3c1dj6j+QKYfnIwQZERyfqrqe+FaHIfB5HHYjPoP0iAFKmlB58XPIiLTt7NQv26o yonRlVYITgy21176x66blhL5AkAMa4TvRkno2/XqbkwC4dW+W2w9Th1e2iAaTYz62R oPN0TwNKKF3PtMljvjL+I3HZ3z104drFV04P0LLPTptEmJ4UozFh2kNDweXk3D+IMz 8ZsKrBAhfHbDg4V7X7Dw484s50jmdVeTVmRXrtoxpHIqHtHFglgHNeTAxDUYatjQBh 74V+mBmqbH4/BnuZ5RuS/qTv1y1HKtQchEiMx8HGnSeSfsfyWbzJurQWFQcsRbCn5I 3zsBoR4hgDM4w== Message-ID: <75c229ef-ae41-4072-9c90-98d4779c52bf@kernel.org> Date: Wed, 14 Oct 2026 12:47:45 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC: DMA_PMD 00/22] DMA_PMD: PMD_SIZE-backed IO buffer pools To: Robin Murphy , Luigi Rizzo Cc: Luigi Rizzo , Joerg Roedel , Will Deacon , Christoph Hellwig , Marek Szyprowski , Andrew Morton , Vlastimil Babka , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Greg Kroah-Hartman , "Rafael J . Wysocki" , Danilo Krummrich , Jonathan Corbet , Jesper Dangaard Brouer , Ilias Apalodimas , Willem de Bruijn , Kuniyuki Iwashima , Joshua Washington , Harshitha Ramamurthy , Saeed Mahameed , Tariq Toukan , Tony Nguyen , Przemek Kitszel , Alexander Lobakin , Michael Chan , Pavan Chebbi , iommu@lists.linux.dev, netdev@vger.kernel.org, linux-mm@kvack.org, driver-core@lists.linux.dev, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org References: <20261003212241.3432303-1-lrizzo@google.com> <0cc1cac1-a500-489b-9c1b-b49598b5550b@kernel.org> <4fda41ed-741b-4c5f-ae83-e3ea5a447441@arm.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <4fda41ed-741b-4c5f-ae83-e3ea5a447441@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 4FE5D180003 X-Stat-Signature: mwtuknppu8hpnqq5if4shu93sy8xtf97 X-HE-Tag: 1791974878-23538 X-HE-Meta: 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 IE9ijov1 ss/eYDp9OnTZJP9sthUUqXD902KUGX+nWbusSzuhi9IjocG+SAypf/fJSopp1yIMkk2H0jiELcfqKP9YYe+n2Qq0+XmcmiUg3tid8E58iukGHn0tcFK0xBtPjJQJetjFNfy296l7ZnQAdto+DxFDedkHaAUyoUIHRsboj6JmKXuSBU8IzGERRCx16mQ0tSZJuZ6q7HT23wbi9fSN5rb1Q3ygYsxdUkf5jNZnK3kWNbBr2Bp87zZmNCpPHb5Q2DtnqE3JBYhsM6nv96fEdf5PXXtYSk2XUaU7RuCsFpoM5+rl/RBLlf5NAVzc3Yv7KxYkCDmn90pZEJzTHHkhPOtLdXlA+DzHIMrRegGRLE8VLq6+sjTiTrpRU/ZZ6XNSu/6x4HAVIMRP5lqymrd+sQQLCo7kvJ0nxlXky/GBDQPB7dzNOa38= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 10/13/26 12:42, Robin Murphy wrote: > On 12/10/2026 8:43 pm, David Hildenbrand (Arm) wrote: >> On 10/12/26 16:45, Luigi Rizzo wrote: >>> On Mon, Oct 12, 2026 at 3:51 PM David Hildenbrand (Arm) >>> wrote: >>> >>> I had to call it something... an earlier prototype used the name IOMMU_2M, >>> but I didn't want to suggest that the design was limited to 2M (it is not). >>> >>> Aside from the name, the _current_ prototype restricts to 2M allocations, >>> exactly because too large units are expensive and wasteful. >>> >>> In the code, decoupling the allocation size from the PMD size is trivial. >> >> Yeah, we should do that. >> >> We should probably just find a way to describe that this is a POOL that focuses >> on physical contiguity in some configured granularity. > And since it's intended for DMA we could call it dma_pool and oh look it already > exists... Heh, I did have "DMA_POOL" in mind when writing my reply. > > Sure the current implementation is capped at PAGE_SIZE for allocation (and thus > mapping too), but I don't see why that couldn't just be made more flexible. That intuitively sounds like the right direction. -- Cheers, David