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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 71603C433EF for ; Fri, 11 Mar 2022 16:51:21 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 9E1158D0002; Fri, 11 Mar 2022 11:51:20 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 98F8D8D0001; Fri, 11 Mar 2022 11:51:20 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 830CD8D0002; Fri, 11 Mar 2022 11:51:20 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.26]) by kanga.kvack.org (Postfix) with ESMTP id 73AAD8D0001 for ; Fri, 11 Mar 2022 11:51:20 -0500 (EST) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 41A08615A1 for ; Fri, 11 Mar 2022 16:51:20 +0000 (UTC) X-FDA: 79232695920.12.400A262 Received: from mga06.intel.com (mga06.intel.com [134.134.136.31]) by imf07.hostedemail.com (Postfix) with ESMTP id 32E1340023 for ; Fri, 11 Mar 2022 16:51:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1647017479; x=1678553479; h=message-id:date:mime-version:to:cc:references:from: subject:in-reply-to:content-transfer-encoding; bh=K0UqcHvbTRf6joZBkaiWA4uWSixwGJw8D96064Fe918=; b=bHDReTP0q88sXCaoPtFq779Rt0ZVz9KwH7kNXI/jclvDUinxAadMbWNP E+fopHi33lH1VR0uO2CPUDJhxDVfPNUYU6sPLWjiRzSNepgdJUHfNs1GK 62KOU0wfyLIikQjMrl+NwoxP/tL345JoxK56iZ2yVPVhBnK1x+3NJ/Q1P YIsjiet6DIYnKzOeUpoUVy3NXzOVuPNvO0SfoZNNl/IALkXzPlVTo5IJC aiuCe6t9zKUQEoGw6YjCvbDDY0OqU2kb7umlxwDlZ9JZoMi+Syqp+1CSn y3ME9hN88xLGUSiitQXuI6dt95qeDp95Pv3jkgPTnoMMJz3W1M91KmUSB Q==; X-IronPort-AV: E=McAfee;i="6200,9189,10283"; a="316329307" X-IronPort-AV: E=Sophos;i="5.90,174,1643702400"; d="scan'208";a="316329307" Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Mar 2022 08:51:17 -0800 X-IronPort-AV: E=Sophos;i="5.90,174,1643702400"; d="scan'208";a="644982258" Received: from cpeirce-mobl1.amr.corp.intel.com (HELO [10.212.128.243]) ([10.212.128.243]) by orsmga004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Mar 2022 08:51:17 -0800 Message-ID: Date: Fri, 11 Mar 2022 08:51:10 -0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Content-Language: en-US To: David Laight , 'Bharata B Rao' , "linux-kernel@vger.kernel.org" Cc: "linux-mm@kvack.org" , "x86@kernel.org" , "kirill.shutemov@linux.intel.com" , "tglx@linutronix.de" , "mingo@redhat.com" , "bp@alien8.de" , "dave.hansen@linux.intel.com" , "catalin.marinas@arm.com" , "will@kernel.org" , "shuah@kernel.org" , "oleg@redhat.com" , "ananth.narayan@amd.com" References: <20220310111545.10852-1-bharata@amd.com> <699fb763ac054833bc8c29c9814c63b2@AcuMS.aculab.com> <286efdb9-7dbf-82f3-b172-29c575a3791b@intel.com> <15fb8774026b4350b2653ce119c85820@AcuMS.aculab.com> <363b91f7-a1d7-b5b5-de86-40bcf61ef818@amd.com> <6191fb9390a9458ca75b73798c3b6d74@AcuMS.aculab.com> From: Dave Hansen Subject: Re: [RFC PATCH v0 0/6] x86/AMD: Userspace address tagging In-Reply-To: <6191fb9390a9458ca75b73798c3b6d74@AcuMS.aculab.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: gcppbbf4ceiei1j8zo5txnemqbo3cs3r Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=bHDReTP0; spf=none (imf07.hostedemail.com: domain of dave.hansen@intel.com has no SPF policy when checking 134.134.136.31) smtp.mailfrom=dave.hansen@intel.com; dmarc=pass (policy=none) header.from=intel.com X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 32E1340023 X-HE-Tag: 1647017478-787935 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 3/11/22 01:36, David Laight wrote: > Wikipedia also notes: > Intel has implemented a scheme with a 5-level page table, which allows > Intel 64 processors to support a 57-bit virtual address space. > Further extensions may allow full 64-bit virtual address space and > physical memory by expanding the page table entry size to 128-bit, > and reduce page walks in the 5-level hierarchy by using a larger 64 KiB > page allocation size that still supports 4 KiB page operations for > backward compatibility. > If they implement 64K pages then you lose the extra bits. I can't believe I need to say this: Wikipedia is not an authoritative source about what anyone is going to do with their CPUs in the future. Please don't base any Linux decisions off this information.