From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-118.freemail.mail.aliyun.com (out30-118.freemail.mail.aliyun.com [115.124.30.118]) (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 A26D7399340 for ; Fri, 26 Jun 2026 02:57:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.118 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782442636; cv=none; b=VacQfxombgAHjibFhA9asoWbGDvxjnihcKawWLDyMunGdKTYuodY5ofoDUlEL4VXuvlGT8huLLwGbMfARP2U8lTNU8YwfzgzrP87VwVeqcQ0jxc4L6FnZQ4PKcejbHFuPkYRXf9+4pZzJMIy1qBUjBpwsRi4BaK+OEg2ij4qTYU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782442636; c=relaxed/simple; bh=ZHgc+xcUJChjAjtuXSpKHzhDpmuoQ9fvcMZXpz9i+W8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=GtG/HgiGoo1SnimYNmUeASezRUUCjPb2IuIiIecP6oXRfFOblmEN8ZRf0DzZfZdcTAxO/1dGFL4r7EFGP+UW5B/M7PuTX8SH3uBBZJKpFax1qeiZOv+85tFHYCGq4mApD+f/0enreBvrttY65PftUalTae7UiofPivQH0rq76zc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=tJLZS2sK; arc=none smtp.client-ip=115.124.30.118 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="tJLZS2sK" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1782442625; h=Date:From:To:Subject:Message-ID:MIME-Version:Content-Type; bh=ufEtd29pwUBu4F3Rcc+nvseTioi8aEp+DuvQJYiFSfc=; b=tJLZS2sKIB5AGMishpE4ruw/DE24j1MRo0AF3ZC26WyibhjygfpXrVMgWckBHbFbUDw3gZfQOIffbzEuhUPqaNyTbHYChm83/kYIx2/WWekj+m3Qd+DG62nufyYTPbWvpsuQlM+t6V8F8aQxrJon/Dw38V8PO0AtENa5j1A77Xs= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R811e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033032089153;MF=feng.tang@linux.alibaba.com;NM=1;PH=DS;RN=12;SR=0;TI=SMTPD_---0X5dL0jF_1782442624; Received: from localhost(mailfrom:feng.tang@linux.alibaba.com fp:SMTPD_---0X5dL0jF_1782442624 cluster:ay36) by smtp.aliyun-inc.com; Fri, 26 Jun 2026 10:57:04 +0800 Date: Fri, 26 Jun 2026 10:57:03 +0800 From: Feng Tang To: Thomas Gleixner Cc: "David Hildenbrand (Arm)" , Andrew Morton , Petr Mladek , Steven Rostedt , paulmck@kernel.org, Douglas Anderson , Peter Zijlstra , Vlastimil Babka , linux-kernel@vger.kernel.org, Ard Biesheuvel Subject: Re: [PATCH v1] kernel: add a simple timer based software watchpoint Message-ID: References: <20260622081430.37557-1-feng.tang@linux.alibaba.com> <0c39c459-306f-49f5-b08e-e7b9b27b6352@kernel.org> <87a4skl36t.ffs@fw13> <87pl1ejoj4.ffs@fw13> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: On Fri, Jun 26, 2026 at 09:56:22AM +0800, Feng Tang wrote: > > > ability to do the virtual to physical address translation instantly to > > > watch a _physical_ address. So I guess, not able to watchpoint a physical > > > address may be common for HW debuggers (I could be very wrong). > > > > If the hardware debugger and the underlying CPU facility (ETM on ARM64 > > IIRC) does not support triggers on physical addresses and you already > > concluded from other information that the problem is in the BIOS, then > > tracing the kernel with it's virt/phys translation is not going to > > work. You obviously have to use the BIOS translation which might be very > > different, no? Forgot to metion, the problem of BIOS was actually enabling some experimental silicon feature, which it should not for this hardware, and then the BIOS wasn't involved in the detail context of the issue. Thanks, Feng > > I didn't explain the issue clearly. The order for solving this issue was, > we first used this method to halt (while (1) dead loop) the system when > detecting the memory corruption, silicon engineers gathered hardware > traces, then root caused it. Before that, we didn't know it's a BIOS issue, > as the initial symptom was random user space "segmentation fault"