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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B2011C433FE for ; Mon, 17 Oct 2022 20:52:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229898AbiJQUwx (ORCPT ); Mon, 17 Oct 2022 16:52:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58300 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229870AbiJQUwu (ORCPT ); Mon, 17 Oct 2022 16:52:50 -0400 Received: from out1-smtp.messagingengine.com (out1-smtp.messagingengine.com [66.111.4.25]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3DD806C75A; Mon, 17 Oct 2022 13:52:49 -0700 (PDT) Received: from compute3.internal (compute3.nyi.internal [10.202.2.43]) by mailout.nyi.internal (Postfix) with ESMTP id A4EB55C0074; Mon, 17 Oct 2022 16:52:48 -0400 (EDT) Received: from imap51 ([10.202.2.101]) by compute3.internal (MEProxy); Mon, 17 Oct 2022 16:52:48 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arndb.de; h=cc :cc:content-type:date:date:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to; s=fm2; t=1666039968; x=1666126368; bh=EK6ZSPGRW5 u+wL3hHxk2To9IvybxeoYZAHIzbHwfh2E=; b=hadaflUK8ppdM2LIUY89Phjffs 5beJBRxoaBA5FSPJsUJgRT3hoVEjT+zJSe809pULnmpSZESJ78donVG7myETWbhQ Mq6Bsw7My7yQnBtNxJBb9W+GMlt25bsdlGAGlNOrPDLI/zrgweZsaY4DyP0L9aOA Normj4uQkY2Cc4feQSgUUhflOAey26K45KHGxCx5ly1EAsN+mZCknCPgz0K1IAbp vR06vM0l70xgk40IUiFCcajp2bAHQw1BmxJAD7x9oITM6AdfIXj0D31hjvm4uCnU kylrGEY+YT/vIZPMQ08zzA5ov2fXqNx2wclyLCRp2LWLdIncXT4mxM87Mx1A== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:date:date:feedback-id :feedback-id:from:from:in-reply-to:in-reply-to:message-id :mime-version:references:reply-to:sender:subject:subject:to:to :x-me-proxy:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s= fm3; t=1666039968; x=1666126368; bh=EK6ZSPGRW5u+wL3hHxk2To9Ivybx eoYZAHIzbHwfh2E=; b=nqa07KGoBUWgXoZbn9TXvvagIRz0pfYKIQXaVkK/r4+i 1e+y7YuwqXjn/9y+BzjaQdqudF47YPjh6OJNIluZZzVaWpLO0FLgOsGGLMk3b6cp NLUfGwx2bRxEOcnRYKEpCkBfmWsz3sharRFTzrqqn0spo59rkQsT+4J++U1kViai NGy2QKcqtq8qIcPFl5dKYMnbUHqSzpO1sSTYK2T+LmspbFq24HJhbXW5Pc01MH7z 69KTIml41oLLnoUaPXqnWFhcRn4SDhemnKIIB0aQX+klVWCrnAT7EFn5GQzLfZuu 11Ze+KrCMb/Ol8KHdbZsKect0LYiM8kiaHT2Kpy/Zg== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvfedrfeekledgudehgecutefuodetggdotefrod ftvfcurfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfgh necuuegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmd enucfjughrpefofgggkfgjfhffhffvvefutgesthdtredtreertdenucfhrhhomhepfdet rhhnugcuuegvrhhgmhgrnhhnfdcuoegrrhhnugesrghrnhgusgdruggvqeenucggtffrrg htthgvrhhnpeffheeugeetiefhgeethfejgfdtuefggeejleehjeeutefhfeeggefhkedt keetffenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpe grrhhnugesrghrnhgusgdruggv X-ME-Proxy: Feedback-ID: i56a14606:Fastmail Received: by mailuser.nyi.internal (Postfix, from userid 501) id C3E40B60086; Mon, 17 Oct 2022 16:52:47 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface User-Agent: Cyrus-JMAP/3.7.0-alpha0-1047-g9e4af4ada4-fm-20221005.001-g9e4af4ad Mime-Version: 1.0 Message-Id: <276d9794-a1b4-4f0d-a9a3-027823038ecc@app.fastmail.com> In-Reply-To: <87sfjmlim3.fsf@mpe.ellerman.id.au> References: <8c7ac4667c6a3cc48f98110117536f60d51ece4a.1665568707.git.christophe.leroy@csgroup.eu> <87sfjmlim3.fsf@mpe.ellerman.id.au> Date: Mon, 17 Oct 2022 22:52:27 +0200 From: "Arnd Bergmann" To: "Michael Ellerman" , "Alexander Gordeev" Cc: "Christophe Leroy" , "Baoquan He" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Linux-Arch , "Andrew Morton" , "Christoph Hellwig" , wangkefeng.wang@huawei.com, schnelle@linux.ibm.com, "David Laight" , "Stafford Horne" , "Benjamin Herrenschmidt" Subject: Re: [RFC PATCH 7/8] mm/ioremap: Consider IOREMAP space in generic ioremap Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 17, 2022, at 2:50 PM, Michael Ellerman wrote: > "Arnd Bergmann" writes: >> >> My guess is that there was no technical reason for this, other >> than having no reason to change the behavior at the time. > > I think the immediate reason for it is that on some CPUs we have to use > 4K pages in the HPT for IO mappings, but PAGE_SIZE == 64K, and we can > only have a single page size per segment (256M or 1T). Right, makes sense. Both the original patch, or the variant with defining IOREMAP_START everywhere seem fine to me then. Arnd