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=-1.4 required=3.0 tests=DATE_IN_PAST_12_24, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 6C780C2BA83 for ; Wed, 12 Feb 2020 15:44:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4CC84206ED for ; Wed, 12 Feb 2020 15:44:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728245AbgBLPod (ORCPT ); Wed, 12 Feb 2020 10:44:33 -0500 Received: from foss.arm.com ([217.140.110.172]:34384 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727026AbgBLPod (ORCPT ); Wed, 12 Feb 2020 10:44:33 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 3FD01328; Wed, 12 Feb 2020 07:44:33 -0800 (PST) Received: from [192.168.122.164] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 081923F68F; Wed, 12 Feb 2020 07:44:33 -0800 (PST) Subject: Re: About PPTT find_acpi_cpu_topology_package() To: John Garry , Sudeep Holla Cc: "Guohanjun (Hanjun Guo)" , ACPI Devel Maling List , "liuqi (BA)" , wanghuiqiang References: <7a888a84-d4c5-2b49-05f3-29876d49cae6@huawei.com> <20200212115945.GA36981@bogus> <20200212135551.GB36981@bogus> <1a04ddf8-4903-2986-a94e-c070dc2c2160@huawei.com> From: Jeremy Linton Message-ID: <3c15a54a-18ac-265e-c16c-272577b9dead@arm.com> Date: Tue, 11 Feb 2020 13:31:43 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <1a04ddf8-4903-2986-a94e-c070dc2c2160@huawei.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org Hi, On 2/12/20 8:41 AM, John Garry wrote: > On 12/02/2020 13:55, Sudeep Holla wrote: >> On Wed, Feb 12, 2020 at 12:48:33PM +0000, John Garry wrote: >>> On 12/02/2020 11:59, Sudeep Holla wrote: >> >> [...] >> > > Hi Sudeep, > >>>> Yes, as mentioned above. We are not going to do extra work for lazy >>>> firmware. >>> >>> I don't think it's reasonable to just label this as lazy. The table >>> may just >>> not have the flag set unintentionally. FW and software guys make >>> mistakes, >>> like the mistakes in PPTT, itself. >>> >> >> We are not talking about flags, it's UID and it is pretty important if >> there are more than one objects of same time. >> > > I am talking about the Processor ID valid flag, which is specifically > related. > >>>> Linux also will be lazy on such platform and provide weird unique >>>> numbers >>>> like in the above case you have mentioned. >>> >>> Personally I think that the kernel can be do better than provide >>> meaningless >>> values like this, since it knows the processor IDs and which physical >>> package they belong to. >>> >> >> This was discussed quite a lot, I can dig and point you to it. That's the >> reason for choosing offset. We are *not going back* to this again. Fix >> the >> firmware before it gets copied for all future platforms and Linux has to >> deal with that *forever*. > > I would liked to have been made aware earlier of the oversight. Quite > often we only find problems when someone or something complains. > > It is a strange API to provide offsets like this, and I did not realize > that they were actually being exposed to userspace. > >> >>> If not, at least make the user know of potential deficiencies in the >>> table. >>> >> >> How ? What are your suggestions ? Does adding a warning or note that UID >> is missing and offset is chosen help ? > > I'd say so. I know now, but let's save others the potential hassle. And > having this debate again. > > I am kind of fine with that. > > How about something like this: > > --- a/drivers/acpi/pptt.c > +++ b/drivers/acpi/pptt.c > @@ -515,6 +515,8 @@ static int topology_get_acpi_cpu_tag(struct > acpi_table_header *table, >   if (level == 0 || cpu_node->flags & ACPI_PPTT_ACPI_PROCESSOR_ID_VALID) >     return cpu_node->acpi_processor_id; > +   if (level == PPTT_ABORT_PACKAGE) > +    pr_warn_once("ACPI Processor ID valid not set for physical package > node, will use node table offset as substitute for UID\n"); To clarify my other email there, since I can't seem to type clearly.. Just note that find_acpi_cpu_topology_hetero_id() is also using a PPTT_ABORT_PACKAGE termination. >                 return ACPI_PTR_DIFF(cpu_node, table); >         } >         pr_warn_once("PPTT table found, but unable to locate core %d > (%d)\n", > > Thanks, > John