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_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 B1B77C2BA83 for ; Wed, 12 Feb 2020 15:32:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8D8C820661 for ; Wed, 12 Feb 2020 15:32:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727519AbgBLPc7 (ORCPT ); Wed, 12 Feb 2020 10:32:59 -0500 Received: from foss.arm.com ([217.140.110.172]:34134 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727026AbgBLPc7 (ORCPT ); Wed, 12 Feb 2020 10:32:59 -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 42937328; Wed, 12 Feb 2020 07:32:58 -0800 (PST) Received: from bogus (e103737-lin.cambridge.arm.com [10.1.197.49]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4050B3F68F; Wed, 12 Feb 2020 07:32:57 -0800 (PST) Date: Wed, 12 Feb 2020 15:32:55 +0000 From: Sudeep Holla To: John Garry Cc: Jeremy Linton , "Guohanjun (Hanjun Guo)" , ACPI Devel Maling List , "liuqi (BA)" , wanghuiqiang , Sudeep Holla Subject: Re: About PPTT find_acpi_cpu_topology_package() Message-ID: <20200212153255.GC36981@bogus> References: <7a888a84-d4c5-2b49-05f3-29876d49cae6@huawei.com> <20200212115945.GA36981@bogus> <20200212135551.GB36981@bogus> <1a04ddf8-4903-2986-a94e-c070dc2c2160@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1a04ddf8-4903-2986-a94e-c070dc2c2160@huawei.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Wed, Feb 12, 2020 at 02:41:04PM +0000, 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. > Ah OK, sorry I had forgotten the specific. I recall it now. > > > > 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. > Agreed. > It is a strange API to provide offsets like this, and I did not realize that > they were actually being exposed to userspace. > We couldn't come up with something that produces same result always and obtained from firmware data. Yes that being in the user-space was the main concern for not generating it in the Linux as we can't guarantee to generate same ID for a given physical socket. Depends on the order in which we boot them or something similar. > > > > > 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. > No argument there. I agree completely. > I am kind of fine with that. > > How about something like this: > Looks good to me. Please post the patch. I am not sure on Rafael's preference on such lengthy warnings(does it need to be split ?) -- Regards, Sudeep