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=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 9A236C2BB84 for ; Mon, 7 Sep 2020 17:54:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2CE7A2080A for ; Mon, 7 Sep 2020 17:54:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="YTUoJOoO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731131AbgIGRy4 (ORCPT ); Mon, 7 Sep 2020 13:54:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42554 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728868AbgIGLWb (ORCPT ); Mon, 7 Sep 2020 07:22:31 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EBDABC061383 for ; Mon, 7 Sep 2020 04:13:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=t6L7mc8LY6HcIK4hTeMOoR+t0IgXAjOkRlYlITQe43E=; b=YTUoJOoOvspRe3TUUiTUlvfdsr FgQbqoTaKbARdHlULynxlhFtt0g40eGclv8PCYn3kNsvM4aZ7Z8L509+iH3WpUmj+FIP0ts4KlWkh mk4KCWTv5noK1r2Y9NQWECqD60MbVBY+Pqon3SXww2yVuVzsOj3Hb1FvU/A9TJB54JditSJyeRvGp kzjD/lBp3G2IHA90Msnd3EWv8ySa33V2k2HBbJXlE6757gxqlejjpZarqYmuIIRBC/9yWmypbMG7n RS5ieIEnUsZcnJ/fsWgLo0QZATtTdWpQNbEGZGFJ1wdSuW50XnbQo6bCbPr0yIRxGO1WaJ2WUWI0q lVSGRgXQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kFF5O-0004ov-Sy; Mon, 07 Sep 2020 11:13:23 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 6151E301179; Mon, 7 Sep 2020 13:13:20 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 438FC20177D0A; Mon, 7 Sep 2020 13:13:20 +0200 (CEST) Date: Mon, 7 Sep 2020 13:13:20 +0200 From: peterz@infradead.org To: Qais Yousef Cc: Dietmar Eggemann , vincent.donnefort@arm.com, mingo@redhat.com, vincent.guittot@linaro.org, linux-kernel@vger.kernel.org, valentin.schneider@arm.com, Phil Auld Subject: Re: [PATCH v2] sched/debug: Add new tracepoint to track cpu_capacity Message-ID: <20200907111320.GP2674@hirez.programming.kicks-ass.net> References: <1598605249-72651-1-git-send-email-vincent.donnefort@arm.com> <20200828102724.wmng7p6je2pkc33n@e107158-lin.cambridge.arm.com> <1e806d48-fd54-fd86-5b3a-372d9876f360@arm.com> <20200828172658.dxygk7j672gho4ax@e107158-lin.cambridge.arm.com> <58f5d2e8-493b-7ce1-6abd-57705e5ab437@arm.com> <20200907104845.6rust2lf2o3d5gmq@e107158-lin.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200907104845.6rust2lf2o3d5gmq@e107158-lin.cambridge.arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 07, 2020 at 11:48:45AM +0100, Qais Yousef wrote: > IMHO the above is a hack. Out-of-tree modules should rely on public headers and > exported functions only. What you propose means that people who want to use > these tracepoints in meaningful way must have a prebuilt kernel handy. Which is > maybe true for us who work in the embedded world. But users who run normal > distro kernels (desktop/servers) will fail to build against But this isn't really aimed at regular users. We're aiming this at developers (IIUC) so I dont really see this as a problem. > FWIW, I did raise this concern with Peter in 2019 OSPM and he was okay with the > exports as it's still not a contract and they can disappear anytime we want. > Migrating to using BTF is the right way forward IMO. I don't think what we have > here is out-of-control yet. Though I agree they're annoying. Right, we're hiding behind the explicit lack of ABI for modules. Anyway, CTF/BTF/random other crap that isn't DWARFs should work fine to replace all this muck. Just no idea what the state of any of that is.