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 CE786F4198E for ; Wed, 15 Apr 2026 10:39:32 +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:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=DKCrW0o6aXpRAmXs22He+QVIMxPsqiY/RjuF4ZJ+/YQ=; b=QPfA3zxm5J3SMklW97eQFgJ+51 2GjsbCZPQ8A+ujFOrm44ZFwDQbaaY/CsJeQ5+JmD37558TuA05tnUMxsxHyI7C+3y2CcIc/LDjyco WWXumTiZHRyS70/7VyUtdzWs0JyfpxWh36wjIRgaStqXHme8TAG18DkJfYfXdH9C0Pke+dP3EWuPS aFa3SymAHedg7Q1vSPS9HG9gIg2k81AKmlUL4cxSpn1/24g61AoCFqDGUzy8XgLdkGK4RV4GnkwV2 LqouqGCA1rAxy2qnz1K+io8dZVMXpM8oc6h51xl4bR+Yify3r3pm/4mSkfIceoB+EXqm346V3G+d6 StJFIkpg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1wCxea-00000000yuY-36lH; Wed, 15 Apr 2026 10:39:28 +0000 Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1wCxeY-00000000yu1-0qQ5 for linux-arm-kernel@lists.infradead.org; Wed, 15 Apr 2026 10:39:27 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id AB1FD41796; Wed, 15 Apr 2026 10:39:25 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0E34BC19424; Wed, 15 Apr 2026 10:39:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776249565; bh=K7RukhB23YR3WJa/P9JAfup97CfUcFnGwXXICQ2wyfU=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=XVrQ8U1P2sxf3hOsdPR0lPOuE6D3Nar/YhKPORu24nsR1fezq+vsIUp3pNck2Xzdy GRaD9MkEQHguAvHKHBJjfXZhnTnqBTDC88jRTaxu71EXop5DWraHOIrEgjH703dbL5 VmisIyiGLxKYAxewY5WOWyCbNmsZGHyki0s5aZdhdnqsswGLkImoiVaNCjK0SpUzU+ XXhrsiGA9TH5mxkSrr75fMytu+O50ZcKARywRPwLaAKhCTwfLQ8OsCAkNothX77YfL gN5rdojqrJSFyK2OgxZ/t6GVfFWSBpndBCJuqMph2Cc/Z3Kf3pQaSKrUWPXMQSyUiI LqjQcc7nMlGBg== Message-ID: <0499741d-56f0-41c3-9256-0b5f9ccc063b@kernel.org> Date: Wed, 15 Apr 2026 12:39:19 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC V1 14/16] arm64/mm: Enable fixmap with 5 level page table To: Anshuman Khandual , linux-arm-kernel@lists.infradead.org Cc: Catalin Marinas , Will Deacon , Ryan Roberts , Mark Rutland , Lorenzo Stoakes , Andrew Morton , Mike Rapoport , Linu Cherian , linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20260224051153.3150613-1-anshuman.khandual@arm.com> <20260224051153.3150613-15-anshuman.khandual@arm.com> <4382c90a-bc92-470e-9aa7-4666753479ca@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260415_033926_284148_9403521E X-CRM114-Status: GOOD ( 11.44 ) 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 4/10/26 05:22, Anshuman Khandual wrote: > > > On 08/04/26 5:59 PM, David Hildenbrand (Arm) wrote: >> On 2/24/26 06:11, Anshuman Khandual wrote: >>> Enable fixmap with 5 level page table when required. This creates table >>> entries at the PGD level. Add a fallback stub for pgd_page_paddr() when >>> (PGTBALE_LEVELS <= 4) which helps in intercepting any unintended usage. >> >> Can you add the "why" ? > > Following reworded commit message should work ? > > ------------------------------------------------------------------ > arm64/mm: Enable fixmap with 5 level page table > > FEAT_D128 halves PTRS_PER_PXX thus shrinking the VA range coverage > for each page table level. Hence in order to preserve all existing > VA range configurations, some geometry now need to become 5-level. > > Since fixmap is used to build and manipulate page tables early on > during boot the mapping must also gain that additional level which > was not required earlier. > > Enable fixmap with 5 level page table when required. This creates table > entries at the PGD level. Add a fallback stub for pgd_page_paddr() when > (PGTBALE_LEVELS <= 4) which helps in intercepting any unintended usage. > ------------------------------------------------------------------- Perfect, thanks! -- Cheers, David