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 6FFE4C4332F for ; Sun, 16 Oct 2022 11:52:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229655AbiJPLw1 (ORCPT ); Sun, 16 Oct 2022 07:52:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58250 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229531AbiJPLwZ (ORCPT ); Sun, 16 Oct 2022 07:52:25 -0400 Received: from wout4-smtp.messagingengine.com (wout4-smtp.messagingengine.com [64.147.123.20]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 522603A4B3; Sun, 16 Oct 2022 04:52:23 -0700 (PDT) Received: from compute3.internal (compute3.nyi.internal [10.202.2.43]) by mailout.west.internal (Postfix) with ESMTP id 404C0320031A; Sun, 16 Oct 2022 07:52:19 -0400 (EDT) Received: from imap51 ([10.202.2.101]) by compute3.internal (MEProxy); Sun, 16 Oct 2022 07:52:20 -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=1665921138; x=1666007538; bh=3j8ISkoR6c dwfWmQo4rJN/bj92WrzimiU8KQFUYoUF0=; b=BwiqToW3oTdY5zXr35/AZUAY86 Rwm1kHuwPS3CtxuwCPPV10aM+fZSs+Wm1T8C7x6OoJCJlnlBGyiz1oZ11AGE+p0D AO71Sdg9wdEAc4YbWVzw3PlNjC2iIzRMoqDwPhkMHee/Be30DQciPSU490SwroEH S1XhXZTmzaffK/+IOlGEEcxhqVs6eaHiOzeeFxziHSAbeN3LSoz4xLdjjCRQhBkf QP9T+bhdlvm/oj5xAYoIr4vPGBg2hVNNQIH2P3cmYW+yN8+jbACLeTWXB/3HjpjD D2Mm9qm4DdtO2W/2pUotuISFbrk6gSUeu6E6Q1vc8iqGPOH1nM7NNmzgKyDQ== 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=1665921138; x=1666007538; bh=3j8ISkoR6cdwfWmQo4rJN/bj92Wr zimiU8KQFUYoUF0=; b=dCq2XjpLGT/z2XwOBjLsH8c0uzJQ0IJen9keOEt6Yct1 593a4qk+PDeJnCF7kOWoHla2MAOjwltIASuFOOqJYl9tRPrJ6HiPI8ToRphpjEel DJ8s4bBZ/3hZu30HAoytUYaHbBKy1lpwRY/oT1n65DIJdUjx6OI1B+MimKBaJP9j TX16kxUzDtXAj5pjUVHm77NJxWvIxbt/8VDmbFpzAacohdCYb8PzKnFSyHsLJJiY KZQHEGPh8/3wQ18o9UE4XZ2GWWwjHGZP9dL/sISOllvtK573zFdpqgsw5XcjifdC caL6JOctDn3qyHvOQYsW2BpgNrR3AjZp8ILYym/h6Q== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvfedrfeekjedggeeiucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhepofgfggfkjghffffhvfevufgtsehttdertderredtnecuhfhrohhmpedftehr nhguuceuvghrghhmrghnnhdfuceorghrnhgusegrrhhnuggsrdguvgeqnecuggftrfgrth htvghrnhepffehueegteeihfegtefhjefgtdeugfegjeelheejueethfefgeeghfektdek teffnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomheprg hrnhgusegrrhhnuggsrdguvg X-ME-Proxy: Feedback-ID: i56a14606:Fastmail Received: by mailuser.nyi.internal (Postfix, from userid 501) id 77C46B60086; Sun, 16 Oct 2022 07:52:17 -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: In-Reply-To: References: <8c7ac4667c6a3cc48f98110117536f60d51ece4a.1665568707.git.christophe.leroy@csgroup.eu> Date: Sun, 16 Oct 2022 13:51:57 +0200 From: "Arnd Bergmann" To: "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 Sun, Oct 16, 2022, at 9:54 AM, Alexander Gordeev wrote: > On Wed, Oct 12, 2022 at 12:39:11PM +0200, Arnd Bergmann wrote: >> "Some" means exactly powerpc64, right? It looks like microblaze >> and powerpc32 still share some of this code, but effectively >> just use the vmalloc area once the slab allocator is up. >> >> Is the special case still useful for powerpc64 or could this be >> changed to do it the same as everything else? > > Or make it the other way around and set IOREMAP_START/IOREMAP_END > to VMALLOC_START/VMALLOC_END by default? Sure, if there is a reason for actually making them different. >From the git history, it appears that before commit 3d5134ee8341 ("[POWERPC] Rewrite IO allocation & mapping on powerpc64"), the ioremap() and vmalloc() handling was largely duplicated. Ben cleaned it up by making most of the implementation shared but left the separate address spaces. My guess is that there was no technical reason for this, other than having no reason to change the behavior at the time. Arnd