From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5029D1ABEDE for ; Wed, 24 Jun 2026 10:21:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782296504; cv=none; b=RQvvNQtDnQtGkw73qzANYgOUIPyvOlJ3s7TQId/KBmIxm+cd/PYDOoP/x+jjF+b2owBiiOc3WMzpm9a35749pHsyjmH7Fh7b1TEUBOp0yN6JHICdYndLBMqBjY6qYqmiT66BMY2761Aqj8dWC6XCWE8VLgt1611aB3W6vP8uxUs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782296504; c=relaxed/simple; bh=rywN9XBs0DRtRomblk5S6sJSsdZo836HqoLNG0kq/uk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=jBjhFOyCkj3XY4Zln0bjFHtQuF0aZJO0Sd7e4rLouIgCLUmtRzDFZVLtPN8l+6bhJhp/RIW6n5Jkhx0frFIuqhtBcqyU8ObW38YTqzsYamlW0BC7c1GncI8o4txauCO7wS4TSBooCN2QXscPgEYABS3HN/r7CUmhuuTLhJPe44E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=gGefgu6M; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="gGefgu6M" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3A25A1F000E9; Wed, 24 Jun 2026 10:21:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782296502; bh=gnIYhzWBuHlN2dZFxelAXBms/gbe/oM9jrXcUg6QXyI=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=gGefgu6M+BkhqCwMAAofWrNnF77MyZTA/bJ6Ek+ZpOQMyro6Ri7RIORI9Q+1DMFOZ 2zO9/140fyAMUBpyMC+ljySt8yyM7qLYszS6X6VsU9sVFFyfsx4+i4G2KgRp8DoCPQ iggr0NQDGiBJEIqnQksdX5x0fv0fJ7E4rbccXE3Xn81OiJgZgZ9BpuGQFvXFW3TVVu QhrZs6TENuugN7LD8kcz5puU6MXngh0PdXZHm+hB1K1QVkDtsk+24RyKh/mCaPEKr2 FE8iQONt3p+Idihne+9bEoRdCieSxA+mmNgbxrubyfacSdXM7lgZk5vbMJT3+yFymD Bj7snWYHUkYTg== Message-ID: Date: Wed, 24 Jun 2026 12:21:38 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1] kernel: add a simple timer based software watchpoint To: Thomas Gleixner , Feng Tang Cc: Andrew Morton , Petr Mladek , Steven Rostedt , paulmck@kernel.org, Douglas Anderson , Peter Zijlstra , Vlastimil Babka , linux-kernel@vger.kernel.org, Ard Biesheuvel References: <20260622081430.37557-1-feng.tang@linux.alibaba.com> <0c39c459-306f-49f5-b08e-e7b9b27b6352@kernel.org> <87a4skl36t.ffs@fw13> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/24/26 11:04, Thomas Gleixner wrote: > On Tue, Jun 23 2026 at 16:26, Feng Tang wrote: >> On Mon, Jun 22, 2026 at 04:13:37PM +0200, David Hildenbrand (Arm) wrote: >> As discussed in RFC patch review, this debug feature is similar to >> soft/hard lockup detector and task-hung detector, should I make the control > > How is this very specialized ad hoc debug magic in any way similar to > generally useful and just working debug mechanism like the lockup or > hung detector? Those are just turned on, do not need a boatload of > command line parameters and are generally useful. > > Your debug magic is a workaround for a disfunctional hardware debugger, > which means it's going to be used by three people twice a year if at > all. Seriously? Jup. As a side note, I worked on hw/sw breakpoint support for VMs in QEMU in the past. So if the problem can be reproduced in a VM, there is the possible alternative of attaching gdb to the gdbserver in QEMU and setting hw/sw breakpoints, including watchpoints. It's primarily focused on memory accesses, of course (not mmio). -- Cheers, David