From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fhigh-a8-smtp.messagingengine.com (fhigh-a8-smtp.messagingengine.com [103.168.172.159]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8E6982472B0; Wed, 10 Sep 2025 15:14:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=103.168.172.159 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757517262; cv=none; b=kSYbA8noEur29S2LyODM54L140o4+u2uSvvPUz4kTUyKwK1xtlwAkrmk16XwKKGAQpL/Q+19+GFBHgBwcmw+KWFwfn30mcI8gI9qTz3ped+zrRsAGCCsDz/uaYq6kRftZUycf20OJ3SAZMxX6bJiPIiE1R5OnCgLKOsFab9+3pQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757517262; c=relaxed/simple; bh=j0peFtksgP54xqAUc1oP7yZ9W8M7m/k54T6JnFegQgM=; h=MIME-Version:Date:From:To:Cc:Message-Id:In-Reply-To:References: Subject:Content-Type; b=jOK3VazoGJmceXiRBI6jxbDtT1wswUrxXwfKd/RaV+25njBT2tvb+cE7MmK66k5Xo3eolDUHkISf+J5W4m6E8uZT2452347qUl3BP0L1P3xv07ry7CVYzzPy+3NKknW4ZapKvFM7J0hrxA393cWIU9TFfFQ8X3on6uOeR3/tR9A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arndb.de; spf=pass smtp.mailfrom=arndb.de; dkim=pass (2048-bit key) header.d=arndb.de header.i=@arndb.de header.b=Wt3vFLdg; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b=H/gMzN7T; arc=none smtp.client-ip=103.168.172.159 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arndb.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arndb.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=arndb.de header.i=@arndb.de header.b="Wt3vFLdg"; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="H/gMzN7T" Received: from phl-compute-05.internal (phl-compute-05.internal [10.202.2.45]) by mailfhigh.phl.internal (Postfix) with ESMTP id C49A01400375; Wed, 10 Sep 2025 11:14:19 -0400 (EDT) Received: from phl-imap-02 ([10.202.2.81]) by phl-compute-05.internal (MEProxy); Wed, 10 Sep 2025 11:14:19 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arndb.de; h=cc :cc:content-transfer-encoding:content-type:content-type:date :date:from:from:in-reply-to:in-reply-to:message-id:mime-version :references:reply-to:subject:subject:to:to; s=fm3; t=1757517259; x=1757603659; bh=lsUUzVSssKb2ZuGuZgzggTzESfnxgxP19f0NGhCBk2A=; b= Wt3vFLdgaWOIw3mFFTO8HkI+FL3aLrAvk1XZkFPK029w4p9kIsmeNNXR2doMLfc2 NQaimD6tWSMhyd9vrBwpPql7GPen65eFUN6bOfqTcjaYKQTvFwR3Tilc07C6ExJ8 jmxdK+IoR3hnYmXzQTnYg/t2INRTwDKScAAC5Zh97EJg6FK42wOtjxbJQG0rbqtx vb435sW48hCiGaDmkSb48ej0GWsn5+SI3ezoINWNC9Mi29MHlc2MYgDudDq3vQpI E3JHV5FX9Je89nP69A4JyLOdFZEUPLOsF/5GLJ2vjV5NifsecRQsRhBZHOY5Wy9x jt6rDjYilo0TVNJQvnJkTg== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-transfer-encoding :content-type:content-type:date:date:feedback-id:feedback-id :from:from:in-reply-to:in-reply-to:message-id:mime-version :references:reply-to:subject:subject:to:to:x-me-proxy :x-me-sender:x-me-sender:x-sasl-enc; s=fm1; t=1757517259; x= 1757603659; bh=lsUUzVSssKb2ZuGuZgzggTzESfnxgxP19f0NGhCBk2A=; b=H /gMzN7TnwJd0vg/MTYVl/pyoe/hmyfwJF4mtR5JWM0w21EGmDqzYq1IsTdotAh60 Fmd1Vg+SdRbChBFHMrAKmV4sr5AgLPgZE/hNEG3iugSyvyKHaye+uflCyTVZE7eW y5OXjXOMEmKkObNDMRZmLutp1NrnRb+HXmB/4TDEu05TLasJXe4OYpexHWqlypFG f5UGmGv6/ug4tXqoJzn54aHwEZlvC1X/XhFICwEees+qOB1PMhCXSGFdzGOeVRCA AmHdT3PYzk6ROQA/RcaMy/7tVU36ZMliytCzRpQYn6smIPsw/Gu6lhjsbjgbm1PQ nnukP2hsdOVcW4iab733Q== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeeffedrtdeggddvfeeivdcutefuodetggdotefrod ftvfcurfhrohhfihhlvgemucfhrghsthforghilhdpuffrtefokffrpgfnqfghnecuuegr ihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjug hrpefoggffhffvvefkjghfufgtgfesthejredtredttdenucfhrhhomhepfdetrhhnugcu uegvrhhgmhgrnhhnfdcuoegrrhhnugesrghrnhgusgdruggvqeenucggtffrrghtthgvrh hnpefhtdfhvddtfeehudekteeggffghfejgeegteefgffgvedugeduveelvdekhfdvieen ucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpegrrhhnug esrghrnhgusgdruggvpdhnsggprhgtphhtthhopedvkedpmhhouggvpehsmhhtphhouhht pdhrtghpthhtoheptghhvghsthgvrhdrrgdruhhnrghlsegrrhhinhgtledrtghomhdprh gtphhtthhopegthhhrihhsthhophhhvgdrlhgvrhhohiestghsghhrohhuphdrvghupdhr tghpthhtoheprghnughrvggrshesghgrihhslhgvrhdrtghomhdprhgtphhtthhopehgvg gvrhhtodhrvghnvghsrghssehglhhiuggvrhdrsggvpdhrtghpthhtoheprghlvgigrghn uggvrhdrshhvvghrughlihhnsehgmhgrihhlrdgtohhmpdhrtghpthhtohepshgvrhhgih hordhprghrrggtuhgvlhhlohhssehgmhgrihhlrdgtohhmpdhrtghpthhtohepshhurhgv nhgssehgohhoghhlvgdrtghomhdprhgtphhtthhopeifihhllhihsehinhhfrhgruggvrg gurdhorhhgpdhrtghpthhtohepihhrrgdrfigvihhnhiesihhnthgvlhdrtghomh X-ME-Proxy: Feedback-ID: i56a14606:Fastmail Received: by mailuser.phl.internal (Postfix, from userid 501) id D18B3700065; Wed, 10 Sep 2025 11:14:17 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface Precedence: bulk X-Mailing-List: ksummit@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ThreadId: AmcCJOTBQ5ho Date: Wed, 10 Sep 2025 17:13:57 +0200 From: "Arnd Bergmann" To: "Matthew Wilcox" , "Linus Walleij" Cc: ksummit@lists.linux.dev, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-mips@vger.kernel.org, linux-mm@kvack.org, imx@lists.linux.dev, "Christophe Leroy" , "Richard Weinberger" , "Lucas Stach" , "Geert Uytterhoeven" , "Ankur Arora" , "David Hildenbrand" , "Mike Rapoport" , "Lorenzo Stoakes" , "Andrew Morton" , "Liam R. Howlett" , "Vlastimil Babka" , "Suren Baghdasaryan" , "Ira Weiny" , "Nishanth Menon" , =?UTF-8?Q?Heiko_St=C3=BCbner?= , "Alexander Sverdlin" , "Chester A. Unal" , "Sergio Paracuellos" , "Andreas Larsson" Message-Id: <55cbc329-4b14-4f62-90bb-1e1007cc1152@app.fastmail.com> In-Reply-To: References: <4ff89b72-03ff-4447-9d21-dd6a5fe1550f@app.fastmail.com> Subject: Re: [TECH TOPIC] Reaching consensus on CONFIG_HIGHMEM phaseout Content-Type: text/plain Content-Transfer-Encoding: 7bit On Wed, Sep 10, 2025, at 16:04, Matthew Wilcox wrote: > On Wed, Sep 10, 2025 at 03:10:05PM +0200, Linus Walleij wrote: >> >> This in practice means the area 0xf1000000-0xffffffff >> which also includes the high exception vectors that must for >> natural reasons also be kept in the mapping. >> What we have mapped today (all of the time) is >> 0xc0000000-0xffffffff. >> >> A minimal 256 MB mapping from 0xf0000000-0xffffffff >> should be able to cover this. > > Can I ask where the MMIO (PCI?) window lives? That 256MB area is shared by anything the kernel can access directly, other than the linear map: vmlinux, modules, vmalloc, ioremap, vmap-stack, etc. This is mostly unchanged from the tradtitional layout on arm32 that has the same ~256MB limitation, though it does get a little tighter because .text/.data is now also mapped into this space instead of executed from the linear map. ARnd