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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,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 85035C43141 for ; Fri, 29 Jun 2018 15:56:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 38CD625038 for ; Fri, 29 Jun 2018 15:56:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 38CD625038 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936839AbeF2P4G (ORCPT ); Fri, 29 Jun 2018 11:56:06 -0400 Received: from foss.arm.com ([217.140.101.70]:36420 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S936157AbeF2P4B (ORCPT ); Fri, 29 Jun 2018 11:56:01 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 267D218A; Fri, 29 Jun 2018 08:56:01 -0700 (PDT) Received: from e107155-lin (unknown [10.1.210.28]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5AADD3F5C0; Fri, 29 Jun 2018 08:55:59 -0700 (PDT) Date: Fri, 29 Jun 2018 16:55:56 +0100 From: Sudeep Holla To: Andrew Jones Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, jeremy.linton@arm.com, ard.biesheuvel@linaro.org, shunyong.yang@hxt-semitech.com, yu.zheng@hxt-semitech.com, catalin.marinas@arm.com, will.deacon@arm.com, Sudeep Holla Subject: Re: [PATCH] arm64: acpi: reenumerate topology ids Message-ID: <20180629155556.GD16282@e107155-lin> References: <20180628145128.10057-1-drjones@redhat.com> <20180628173243.obydzakh2stfs26w@kamzik.brq.redhat.com> <20180629102927.GA18043@e107155-lin> <20180629112354.hefdl2pe72frl6x3@kamzik.brq.redhat.com> <20180629132934.GA16282@e107155-lin> <20180629154608.nqudibf54ti6dpjc@kamzik.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180629154608.nqudibf54ti6dpjc@kamzik.brq.redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 29, 2018 at 05:46:08PM +0200, Andrew Jones wrote: > On Fri, Jun 29, 2018 at 02:29:34PM +0100, Sudeep Holla wrote: [..] > > > > How is that different from OS generated one from user's perspective ? > > Vendors might assign sockets UID and he may help them to replace one. > > Having some generated counter based id is not helpful. > > I agree with this. It's a good argument for maintaining a mapping of > package-id to id-physically-printed-on-a-package somewhere. To avoid > maintaining a mapping it could just be stored directly in > cpu_topology[cpu].package_id, but then how can we tell the difference > between a valid printed-on-package-id and an ACPI offset? We'd still > have to maintain additional state to determine if it's valid or not, > so we could just maintain a mapping instead. > x86 may have a architectural way to obtain it and hence they don't need to rely on PPTT. But for ARM, we need to rely on PPTT for it and if vendors/users need accurate information, it has to come from PPTT and any other place is never going to be consistent and hence unusable. So, even though specification doesn't mandate, I think OS should as it's the only robust way. We can get the firmware fixed/updated if random unique number hurts. Firmware is not upgradeable is no longer a valid argument. -- Regards, Sudeep From mboxrd@z Thu Jan 1 00:00:00 1970 From: sudeep.holla@arm.com (Sudeep Holla) Date: Fri, 29 Jun 2018 16:55:56 +0100 Subject: [PATCH] arm64: acpi: reenumerate topology ids In-Reply-To: <20180629154608.nqudibf54ti6dpjc@kamzik.brq.redhat.com> References: <20180628145128.10057-1-drjones@redhat.com> <20180628173243.obydzakh2stfs26w@kamzik.brq.redhat.com> <20180629102927.GA18043@e107155-lin> <20180629112354.hefdl2pe72frl6x3@kamzik.brq.redhat.com> <20180629132934.GA16282@e107155-lin> <20180629154608.nqudibf54ti6dpjc@kamzik.brq.redhat.com> Message-ID: <20180629155556.GD16282@e107155-lin> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, Jun 29, 2018 at 05:46:08PM +0200, Andrew Jones wrote: > On Fri, Jun 29, 2018 at 02:29:34PM +0100, Sudeep Holla wrote: [..] > > > > How is that different from OS generated one from user's perspective ? > > Vendors might assign sockets UID and he may help them to replace one. > > Having some generated counter based id is not helpful. > > I agree with this. It's a good argument for maintaining a mapping of > package-id to id-physically-printed-on-a-package somewhere. To avoid > maintaining a mapping it could just be stored directly in > cpu_topology[cpu].package_id, but then how can we tell the difference > between a valid printed-on-package-id and an ACPI offset? We'd still > have to maintain additional state to determine if it's valid or not, > so we could just maintain a mapping instead. > x86 may have a architectural way to obtain it and hence they don't need to rely on PPTT. But for ARM, we need to rely on PPTT for it and if vendors/users need accurate information, it has to come from PPTT and any other place is never going to be consistent and hence unusable. So, even though specification doesn't mandate, I think OS should as it's the only robust way. We can get the firmware fixed/updated if random unique number hurts. Firmware is not upgradeable is no longer a valid argument. -- Regards, Sudeep