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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 A9A71C33CAF for ; Thu, 16 Jan 2020 20:20:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7FF3B206D9 for ; Thu, 16 Jan 2020 20:20:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579206006; bh=oko1vr6NZIkbqblBi6ADclwFu8hYoUF6zOgs+mmCjwY=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=efmBtKw9Tl0PrICe+EkNirqrZqXkQwslukxBSLs0fzaskSHI0vy9uxY7FQFVjtN6m mBnY2NTHXbpNcKvhUAb2eMfmOSjaAMQS3rFhsJWdMiOwoToAnUqqO/Uv+NuO0oUeH+ UDLMsY5Ybqfuzx1iQSsFWUVIXgxscIf8LZAAYM5A= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733244AbgAPUUF (ORCPT ); Thu, 16 Jan 2020 15:20:05 -0500 Received: from mail.kernel.org ([198.145.29.99]:38550 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727022AbgAPUUF (ORCPT ); Thu, 16 Jan 2020 15:20:05 -0500 Received: from mail-wm1-f42.google.com (mail-wm1-f42.google.com [209.85.128.42]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0AB0C2081E for ; Thu, 16 Jan 2020 20:20:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579206004; bh=oko1vr6NZIkbqblBi6ADclwFu8hYoUF6zOgs+mmCjwY=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=L+rMfwJVUI9W+d2CoFvavrawmV6XxbnS/C5pFOW3GNaz/dDJWJPZM8duGoLOAL4lG Z02NHO/8MGKmfFb7GIu6L6UBs5VQJuL2gCzfJtQIf5HIZsqZ0+yd6MnHhIphnFuyoZ f3RLMs/ybk1B0MMAwdTLCraQ7qACz4TRbZO2ykR0= Received: by mail-wm1-f42.google.com with SMTP id q9so5124735wmj.5 for ; Thu, 16 Jan 2020 12:20:03 -0800 (PST) X-Gm-Message-State: APjAAAXIOeAdWHYffJJKftFocKyW3tv5jiwtrT9dxnVnxyQyfIPFKGj6 NQ3NF6GUufaPVfm8qb1H/soLO2pPPelGu7YaPzUaGA== X-Google-Smtp-Source: APXvYqy/LKhOLCc4c+qZpvX/KQlnVohcy3HlKPdTJR43s7e+TgAW2p8Y+rne7KnqV+o60SXTwTHEOrPWPUde8RosJLE= X-Received: by 2002:a05:600c:20c7:: with SMTP id y7mr794016wmm.21.1579206002474; Thu, 16 Jan 2020 12:20:02 -0800 (PST) MIME-Version: 1.0 References: <1b278bc1f6859d4df734fb2cde61cf298e6e07fd.1579196675.git.christophe.leroy@c-s.fr> <874kwvf9by.fsf@nanos.tec.linutronix.de> In-Reply-To: <874kwvf9by.fsf@nanos.tec.linutronix.de> From: Andy Lutomirski Date: Thu, 16 Jan 2020 12:19:50 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [RFC PATCH v4 08/11] lib: vdso: allow fixed clock mode To: Thomas Gleixner Cc: Christophe Leroy , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , nathanl@linux.ibm.com, Arnd Bergmann , Vincenzo Frascino , Andrew Lutomirski , LKML , linuxppc-dev , linux-arm-kernel , "open list:MIPS" , X86 ML Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 16, 2020 at 12:14 PM Thomas Gleixner wrote: > > Christophe Leroy writes: > > Can you please adjust the prefix for future patches to lib/vdso: and > start the sentence after the colon with an uppercase letter? > > > On arches like POWERPC, the clock is always the timebase, it > > Please spell out architectures. Changelogs are not space constraint. > > > cannot be changed on the fly and it is always VDSO capable. > > Also this sentence does not make sense as it might suggests that > architectures with a fixed compile time known clocksource have something > named timebase. Something like this is more clear: > > Some architectures have a fixed clocksource which is known at compile > time and cannot be replaced or disabled at runtime, e.g. timebase on > PowerPC. For such cases the clock mode check in the VDSO code is > pointless. > I wonder if we should use this on x86 bare-metal if we have sufficiently invariant TSC. (Via static_cpu_has(), not compiled in.) Maybe there is no such x86 machine. I really really want Intel or AMD to introduce machines where the TSC pinky-swears to count in actual nanoseconds. --Andy