From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id D4AFF47F2E0 for ; Mon, 5 Oct 2026 13:15:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791206137; cv=none; b=ZkqmbRj1UjPW73kQq20btsh2g04epGWv7jW2Lsh20vO/ld82vJdG+CqyV+fwzVzlcZS1W+eXBI/Wvz6RNBT1u8a1daYH9bxzV3uFyi7V4O7qqfAMztRGzgSMYS9BCV5q7mM4XLd7zNu7NJ9B4dGmPZI17qmlSMKOCyp/GIVYmMk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791206137; c=relaxed/simple; bh=m3tmSH0+leL7BS79iE/YdCgWfzPU9HDRqYcmSoRJD60=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=gAoswqGTxhCkMayw6kmnP0c6CqFBejdehw1I+mj2JiNVjZY3Pdh/+Zsbn01WWCmJARZ+499GFZdFfx4e0YBO9fym0rGHS5ZjIIfsDlt9lMzByCrAz+reI7uGOZsTrYO/vorZs8p50gLMJppx+DmRXG4r/grEGCwfwp3JIQGRw/g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=KIoe/8CV; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="KIoe/8CV" 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 6C187152B; Mon, 5 Oct 2026 06:15:31 -0700 (PDT) Received: from [10.2.212.23] (e121345-lin.cambridge.arm.com [10.2.212.23]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 43B0C3F86F; Mon, 5 Oct 2026 06:15:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1791206134; bh=m3tmSH0+leL7BS79iE/YdCgWfzPU9HDRqYcmSoRJD60=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=KIoe/8CVD+wIe5QvHf9R7AMxlQqGiVNz0V7h5QPw/ZHk2OZsH79wmWEzt9Y1FfqzX ZwsAJ3IoJNBq2cwafU4UjpJMqKW6zdpFuJFYIwSYCjQwsWSP+CbwK11PYGo8zrCCQa FZMAltM8TzJtX3bWD+Hw3zF3f5wPv7kbo7+WdpbY= Message-ID: <426110f0-0ef4-4f15-b68f-103a863df3aa@arm.com> Date: Mon, 5 Oct 2026 14:15:32 +0100 Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] perf: Add Arm Bus Monitor Unit driver To: Will Deacon Cc: mark.rutland@arm.com, linux-perf-users@vger.kernel.org, linux-arm-kernel@lists.infradead.org References: From: Robin Murphy Content-Language: en-GB In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 04/10/2026 11:10 pm, Will Deacon wrote: > On Thu, Sep 17, 2026 at 02:47:12PM +0100, Robin Murphy wrote: >> Arm's Bus Monitor Unit is a low-level performance analysis tool for >> matching and counting transactions at interconnect interfaces. Each >> BMU consists of a number of "interface monitoring units", with some >> global controls to synchronise them and so permit accurate calculation >> of cross-interface metrics. Each IMU contains, among other things, its >> own PMU largely based on the CoreSight PMU architecture, but with some >> functional incompatibilities due to the nature of how much per-event >> filtering needs to be crammed in to categorise AXI/CHI transactions at >> the protocol level. As such it gets an honorary home in arm_cspmu/ in >> order to share the common register definitions, but for simplicity does >> not try to bend the functional abstraction to fit. >> >> Signed-off-by: Robin Murphy >> >> --- >> v3: >> - Couple of inconsequential tweaks to shut Sashiko up about things >> that would never actually happen anyway >> - Drop unneeded DT patches that I can't be bothered to fix right now > > Please can you take a look at the Sashiko comments on this one? I did start writing a reply at the time, but it was getting so sarcastic that even I thought better of sending it... In (polite) summary: 1 - Gibberish 2 - Yes if firmware blatantly mis-describes the hardware then Linux may not work properly. Whoop de do. 3 - Yeah so? 4 - Pants-on-head gibberish, but the second part about COMPILE_TEST is fair (an oversight from ripping out the DT support) - fix is already in -next via the ACPI tree[1] 5 - Yeah so? 6,7 - Yes, welcome to perf... Cheers, Robin. [1] https://lore.kernel.org/all/CAJZ5v0g4k6FhyQMypkRyVJMkSBUsmeuetJuxRA826PcA7Mo5Hg@mail.gmail.com/