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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E1D86C04A68 for ; Wed, 27 Jul 2022 19:14:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232628AbiG0TOp (ORCPT ); Wed, 27 Jul 2022 15:14:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34448 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237440AbiG0TOP (ORCPT ); Wed, 27 Jul 2022 15:14:15 -0400 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 7C6445722D; Wed, 27 Jul 2022 12:01:33 -0700 (PDT) Received: from kbox (unknown [76.135.27.191]) by linux.microsoft.com (Postfix) with ESMTPSA id 0C9AA20FE6EB; Wed, 27 Jul 2022 12:01:33 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 0C9AA20FE6EB DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1658948493; bh=Fw60Yf0VMd9Jf3E1H5eEjH/hmBkB5bsPe9qB4NufJHI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=hSm2H0MC4hFXtvVDIbhUQmRo+X5iR3VSGKcfxB+f2NoIVzCIWDH1z1jAgcGe0unl8 3OJIpsNOrlLE+fW+Tp630EkfgIZUE4lyabjcvELRwg6rbkdi6mM2sCcHOaWWk0atRa QN8QSX51jMIen9erg8ZKBh3oO62zYf5/cvjqel1w= Date: Wed, 27 Jul 2022 12:01:25 -0700 From: Beau Belgrave To: Steven Rostedt Cc: mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-devel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Subject: Re: [PATCH v2 6/7] tracing/user_events: Use bits vs bytes for enabled status page data Message-ID: <20220727190125.GA1735@kbox> References: <20220425184631.2068-1-beaub@linux.microsoft.com> <20220425184631.2068-7-beaub@linux.microsoft.com> <20220726180115.69320865@gandalf.local.home> <20220727000249.GA2289@kbox> <20220726201412.7fbd3b1f@rorschach.local.home> <20220727020147.GA1705@kbox> <20220727094517.25e9dee5@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220727094517.25e9dee5@gandalf.local.home> Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org On Wed, Jul 27, 2022 at 09:45:17AM -0400, Steven Rostedt wrote: > On Tue, 26 Jul 2022 19:01:47 -0700 > Beau Belgrave wrote: > > > Ah, I see the confusion. Sorry. > > > > EVENT_STATUS_* are internal bits that aren't used with STATUS_MASK or > > STATUS_BYTE. It's only used to set and check the user event status byte > > for checking if anything is attached and outputting which probe is > > connected within the kernel side. > > > > STATUS_BYTE and STATUS_MASK take a bit in a bitmap and figure out which > > byte in the status mapping should be used and which bit in that byte > > should be set/reset (mask) when it's enabled/disabled via a probe. Both > > the user and kernel need to align on this logic. > > > > IE: Bits above the lower 3 of the index/bit of the event to enable is the byte > > and the lower 3 bits (& 7) is the actual bit to set. > > > > For example if the user_event with the index 1024 is enabled, we need to > > figure out which byte and bit represents that event when a probe is > > attached. > > > > I got into detail of this in the documentation for both a byte and long > > wise checking of these values. > > > > Hope that helps explain it. > > Yes, but that should be in the comments above the code. > Will do, I will also change to use the BIT() macro as you suggested. > -- Steve Thanks, -Beau