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 B2DA33B777F for ; Mon, 22 Jun 2026 14:13:41 +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=1782137622; cv=none; b=A1yW/oVpzuxQumDN5A2Udq5oLIKlmyLgrEgGLn+uG4r/q3NzkWNvEQPrDOJezpZf1h98JRwhEhAt2zK7JPjnWDp5+1zx742f2SBlBuIoPRTXjxplluhIWiG65GazVU9Q0uCx0UVzwlInFPRibQlK/TsaikaFYe0+zxuKawvFdzA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782137622; c=relaxed/simple; bh=UY/BXSlcDf0x0Y8CZEvTpWSqOzYxIdn53HFYowZwNwA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=AQsMvXeRb+rNbpq9/fPwomymlugNP9KVtidi5LnZ6ckTnzXszyfa6nxTT5b72oCNDCFAiKwEmKaiyqh0aQZJQ5yRurxoxobydrrzNVpuN75jPQRJqkpYR60egUmuUqJeI5zMhnXi0PVO4cyynP++PFdhYchPrRDZ4MqvqY7rqy4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ANefRJvI; 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="ANefRJvI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 74DF21F000E9; Mon, 22 Jun 2026 14:13:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782137621; bh=56/rgJJsLQpj8bBKBncTd5ebtfg//O3RIDmqdm4icV4=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=ANefRJvIkRQbijIHYt1q7vgPC3wZIdR1rYccrCuP65HjFFiM/yb6v3QxMOsLGMn/m K0PWKr45JD5jv1aUP9CxbFVn063+lkNj8ZIKFtB+LqWOqgntohW1RoIhtunOFOYMtP mkt7P6ugUn9kSHNDa6LabLGHyWjvtVJBXbl8Di+HLgQtl+34gUCWD/nONVJ5vBIZEq kTxRPYO7ODmlZdiMxGVycgZM9MO77n7ZRaJKrfb+u3lFIyMXqXlTVjYe1pXeCQ37eQ z4I/JFJ5ZgJleItrP1zezcr2zsnaOEoKhIlMmPtfQr+6A7c9VDzlMJM+zRujH/vCzh +gJCYotiNmKEw== Message-ID: <0c39c459-306f-49f5-b08e-e7b9b27b6352@kernel.org> Date: Mon, 22 Jun 2026 16:13:37 +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: Feng Tang Cc: Andrew Morton , Petr Mladek , Steven Rostedt , paulmck@kernel.org, Douglas Anderson , Thomas Gleixner , Peter Zijlstra , Vlastimil Babka , linux-kernel@vger.kernel.org, Ard Biesheuvel References: <20260622081430.37557-1-feng.tang@linux.alibaba.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit >>> This provides the basic function, and there are more todoes: >>> * add a ftrace mode to do function level monitoring with ftrace hook, >>> which is more accurate timing wise, as suggested by Steven Rostedt >>> * merge the dram/mmio interface to auto detect it's dram or mmio >>> * support runtime changing the address >>> * move the starting point earlier in boot phase >>> * monitor a whole memory region >>> * currently is monitoring 'changing to a value', add support >>> for 'changing from a value' >> >> That really looks more like the kind of thing you would want to carry as a OOT >> hack for your special debugging needs :) > > Thanks for the review and bringing up a very good question that whether > the patch is worthy! > > Personally, I think it is. The problem is that the interface is odd (kernel parameters) and the implementation is shaky (what happens if memory does not exist? What happens if we unplug memory?). I don't think it's a good use of our time to polish all that up and then maintain it. -- Cheers, David