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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 63E32C282DF for ; Fri, 19 Apr 2019 18:37:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3C26E204EC for ; Fri, 19 Apr 2019 18:37:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728387AbfDSShx (ORCPT ); Fri, 19 Apr 2019 14:37:53 -0400 Received: from mga18.intel.com ([134.134.136.126]:62980 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726960AbfDSShv (ORCPT ); Fri, 19 Apr 2019 14:37:51 -0400 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 19 Apr 2019 10:16:10 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,370,1549958400"; d="scan'208";a="163345283" Received: from unknown (HELO localhost.localdomain) ([10.232.112.69]) by fmsmga004.fm.intel.com with ESMTP; 19 Apr 2019 10:16:09 -0700 Date: Fri, 19 Apr 2019 11:09:59 -0600 From: Keith Busch To: Alison Schofield Cc: "Rafael J. Wysocki" , "Rafael J. Wysocki" , Robert Moore , "Schmauss, Erik" , ACPI Devel Maling List , Linux Kernel Mailing List Subject: Re: [PATCH] acpi/hmat: Update acpi_hmat_type enum with ACPI_HMAT_TYPE_PROXIMITY Message-ID: <20190419170958.GA9331@localhost.localdomain> References: <20190417181310.27613-1-alison.schofield@intel.com> <20190418145640.GA7659@localhost.localdomain> <20190419165435.GA2284@alison-desk.jf.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190419165435.GA2284@alison-desk.jf.intel.com> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 19, 2019 at 09:54:35AM -0700, Alison Schofield wrote: > On Thu, Apr 18, 2019 at 05:07:12PM +0200, Rafael J. Wysocki wrote: > > On Thu, Apr 18, 2019 at 5:02 PM Keith Busch wrote: > > > > > > On Wed, Apr 17, 2019 at 11:13:10AM -0700, Alison Schofield wrote: > > > > ACPI 6.3 changed the subtable "Memory Subsystem Address Range Structure" > > > > to "Memory Proximity Domain Attributes Structure". > > > > > > > > Updating and renaming of the structure was included in commit: > > > > ACPICA: ACPI 6.3: HMAT updates (9a8d961f1ef835b0d338fbe13da03cb424e87ae5) > > > > > > I was not really happy with that HMAT update. Platforms implementing > > > 6.2's HMAT continue to exist even if 6.3 isn't backward compatible. We > > > just lost the original subtable definition. > > > > Well, that's true, sadly, but the question is what to do in the kernel. > > > > Definitely, the 6.3 format needs to be supported, but if the 6.2 ships > > anywhere in practice, that will need to be supported too. > > So, what's the usual practice when ACPI tables are updated? > Do we define separate 6.2 and 6.3 versions of this subtable and let > the kernel figure out which one its looking at? Yeah, I think either new struct definitions for incompatible versions, or unions for conflicting members would be good. But I think Rafael is saying we only care if someone's shipping platform implements a particular version. I don't happen to know which ACPI version platforms I'm interested are going to release with, so I have HMAT supporting either right now. The 6.3 update wasn't difficult to handle this time.