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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4D280CAC583 for ; Wed, 10 Sep 2025 14:05:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=mKSB+4xL7cCmeYE/ZtEdtCjsvm7CIgVIfr0teJIjFAU=; b=ZcleUnDAYcWO2U1bUwhth4fpV3 iU0EIp6WnWyyLKFLcdGjPQXwGzH/9VkbrJs+vVqTQR7YQRSNl5ZYuAQ4pfEJtQE6F95ouv0+iWT68 WtZA2osBIsMz0UoRYOIU08cTCrc+2sWOgNuYTSiEU8rZkiKgO0TN73w+ctpDKnKL3y1E8TqjzwcAh wt4mSL+31EpINGj9dgBQR9+1czwpTgVNYMwzs5EXizr+80UCqQT3oetvoOVZvZH08RRc2hT+Akdqm hlZBpeCDPd6Z2+QuhcOUsW4a5BVUTs+pX0u5/7hunRqQ0TUrXJZqbuzLyE3svPDv8dOTZOMQmNHFv eP2PXhXQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uwLRU-0000000EZdK-436T; Wed, 10 Sep 2025 14:05:00 +0000 Received: from casper.infradead.org ([2001:8b0:10b:1236::1]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uwLRT-0000000EZby-0BwF for linux-arm-kernel@bombadil.infradead.org; Wed, 10 Sep 2025 14:04:59 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; 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=mKSB+4xL7cCmeYE/ZtEdtCjsvm7CIgVIfr0teJIjFAU=; b=dofEW7af/ejhmNipPt2aD1zjQc r/T1X53PF0e+BEfGBFGmptVoarxZBEN1Hr7xriD76R1w+M+nvAcyFt2PcHdzuHg+TQmoMQFUdBQaA jm/o6jj1rPqB5i/QW6QVLU4W6O2YAUS0S3TvZPMLDfVQol1YTS76QR+/j8xxBFEpwnMLWAqId4scS bdUpC9Pcr4BH4JRwC/mCjcKWJe0ye/ZaEnL2OllK0B+92NxsmXiDMXLQP/kJYOtEetOYDdThozbzr U+eiVsgCMI71Rea2iE366+z3/3jQiRamjgJEHnieliGZegYbRdaVVmJTC4g6lcXbzYemC7sUUzZ3A gI/iBz2w==; Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1uwLRO-0000000A1bz-3lAQ; Wed, 10 Sep 2025 14:04:54 +0000 Date: Wed, 10 Sep 2025 15:04:54 +0100 From: Matthew Wilcox To: Linus Walleij Cc: Arnd Bergmann , 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 , Heiko =?iso-8859-1?Q?St=FCbner?= , Alexander Sverdlin , "Chester A. Unal" , Sergio Paracuellos , Andreas Larsson Subject: Re: [TECH TOPIC] Reaching consensus on CONFIG_HIGHMEM phaseout Message-ID: References: <4ff89b72-03ff-4447-9d21-dd6a5fe1550f@app.fastmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Sep 10, 2025 at 03:10:05PM +0200, Linus Walleij wrote: > This is is done so that we can unmap *most* of the kernel > memory but *keep* the VMALLOC area, so that e.g. exceptions > can still execute and save to stack when they occur, and we can > call into the kernel to execute said exceptions. > > 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?