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 X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3B932C433E0 for ; Fri, 15 Jan 2021 03:49:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 02EA822CBE for ; Fri, 15 Jan 2021 03:49:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728452AbhAODty (ORCPT ); Thu, 14 Jan 2021 22:49:54 -0500 Received: from mga03.intel.com ([134.134.136.65]:53969 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727116AbhAODty (ORCPT ); Thu, 14 Jan 2021 22:49:54 -0500 IronPort-SDR: QqFEGtEaJcrIwAc6syNn3+VwAWqoEH0XoWA50lB24uGbczzj+/mNNXUgrgLgS2RsMvDcvFBcab NfJe7DRUyNjA== X-IronPort-AV: E=McAfee;i="6000,8403,9864"; a="178578736" X-IronPort-AV: E=Sophos;i="5.79,348,1602572400"; d="scan'208";a="178578736" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Jan 2021 19:49:13 -0800 IronPort-SDR: nI0l5cZaUWU+Zsj5BL+QF2TfJ3e47MPhnHfVJjuGJI9tho79G3WwYJKX/20HkGgLht1PMQ2MYs MMpG/ZC+NA+g== X-IronPort-AV: E=Sophos;i="5.79,348,1602572400"; d="scan'208";a="382513151" Received: from yulungsu-mobl.amr.corp.intel.com (HELO intel.com) ([10.252.129.206]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Jan 2021 19:49:13 -0800 Date: Thu, 14 Jan 2021 19:49:11 -0800 From: Ben Widawsky To: "Verma, Vishal L" Cc: "linux-cxl@vger.kernel.org" , "linux-acpi@vger.kernel.org" , "Williams, Dan J" , "Douglas, Chet R" Subject: Re: ACPI Working Group Code First ECR for a new CXL Root Object Message-ID: <20210115034911.nkgpzc756d6qmjpl@intel.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On 21-01-14 19:17:52, Verma, Vishal L wrote: > On Thu, 2020-12-03 at 20:12 +0000, Verma, Vishal L wrote: > > This is a public RFC of an ACPI proposal to add a new CXL Root Object > > that indicates the presence of a CXL hierarchy. The proposal is being > > made in the new 'Code First' workflow of the ACPI Spec Working Group. > > The subject matter here has been explored in previously posted patches > > to QEMU[1] as well as Linux[2]. These patches have served as a proof-of- > > concept test vehicle to help ensure that the proposal works in practice. > > The cover letter in series [2] goes into additional detail (section > > titled 'ACPI0017') for the reasoning behind the proposal, and what is > > needed beyond what's described in the CXL 2.0 spec. > > > > The change proposal that follows is in markdown format. > > > > [1]: https://lore.kernel.org/qemu-devel/20201111054724.794888-1-ben.widawsky@intel.com/ > > [2]: https://lore.kernel.org/linux-cxl/20201111054356.793390-1-ben.widawsky@intel.com/ > > > > ---- > > > > # Title: Add CXL Root Object _HID > > > > # Status: Draft > > This ECR was approved in the ASWG today without any modifications, and > this content can be expected to be present in the next release of the > specification. > Nice job Vishal! > > > > # Document: ACPI Specification 6.4 > > > > # License > > SPDX-License Identifier: CC-BY-4.0 > > > > # Submitter: > > * Sponsor: Vishal Verma, Intel > > * Creators/Contributors: > > * Chet Douglas, Intel > > * Ben Widawsky, Intel > > * Dan Williams, Intel > > * Vishal Verma, Intel > > > > # Summary of the Change > > Add “Compute Express Link Root Object” enumeration value to the ACPI > > Device IDs Table (5.160). > > > > # Benefits of the Change > > Compute Express Link (CXL) is a new high-speed CPU-to-Device and CPU-to- > > Memory interconnect. The new ACPI Device ID represents a singleton > > device that allows the OSPM to trigger the enumeration of the CXL.mem > > address space, and indicates the presence of cross Host Bridge > > (ACPI0016) interleaved CXL.mem resources. > > > > # Impact of the Change > > One new row added to the ACPI Device IDs table (5.160). > > > > # References > > * Compute Express Link Specification v2.0, > > > > > > # Detailed Description of the Change > > > > Add “Compute Express Link Root Object” enumeration device > > > > ### 5.6.7 Device Class-Specific Objects > > > > Most device objects are controlled through generic objects and ... > > > > Table 5.160 ACPI Device IDs > > > > > Value | Description | > > > :--- | :---: | :---: | :--------------------------- | > > > .. | .. | > > > ACPI0017 | **Compute Express Link Root Object:** This device > > represents the root of a CXL capable device hierarchy. It shall be > > present whenever the platform allows OSPM to dynamically assign CXL > > endpoints to a platform address space. | > > > > ## Special Instructions >