From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756038AbYDFRdB (ORCPT ); Sun, 6 Apr 2008 13:33:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754885AbYDFRcx (ORCPT ); Sun, 6 Apr 2008 13:32:53 -0400 Received: from pne-smtpout4-sn2.hy.skanova.net ([81.228.8.154]:42416 "EHLO pne-smtpout4-sn2.hy.skanova.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754880AbYDFRcw (ORCPT ); Sun, 6 Apr 2008 13:32:52 -0400 Date: Sun, 6 Apr 2008 20:32:21 +0300 From: Pekka Paalanen To: Avi Kivity , Ingo Molnar Cc: linux-kernel@vger.kernel.org, Christoph Hellwig , Arjan van de Ven , Pavel Roskin , Steven Rostedt , Peter Zijlstra , penberg@cs.helsinki.fi, vegard.nossum@gmail.com Subject: Re: mmiotrace bug: recursive probe hit Message-ID: <20080406203221.39378390@daedalus.pq.iki.fi> In-Reply-To: <47F72C12.9020701@qumranet.com> References: <20080309164050.2194461e@daedalus.pq.iki.fi> <20080328222500.21863a44@daedalus.pq.iki.fi> <20080330202608.054702a4@daedalus.pq.iki.fi> <20080404000701.70bbc1a4@daedalus.pq.iki.fi> <47F72C12.9020701@qumranet.com> X-Mailer: Claws Mail 3.0.2 (GTK+ 2.12.8; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 05 Apr 2008 10:36:50 +0300 Avi Kivity wrote: > However there is a simpler (for you) > solution: run the driver-to-be-reverse-engineered in a kvm guest, and > modify kvm userspace to log accesses to mmio regions. This requires the > not-yet-merged pci passthrough support. You can reverse engineer > Windows drivers with this as well. This is a very interesting idea, I didn't know it would be possible. I think this also is a new project and I'd be happy to let someone else take it over. We could still use the log format and tools from mmiotrace, at least for starters. This puts mmiotrace in a new ligth: there's something better(?) coming in the future. But mmiotrace is here now, and I'd still like to see it in mainline. Within ftrace framework, mmiotrace will be very easy to use even for a Linux newbie. The KVM approach would be targeted to developers, as I suspect setting it up (even when everything has been merged into mainline) is more work than running mmiotrace. Ingo, what do you think? In my opinion let's make mmiotrace force the system down to UP via CPU hotplugging while MMIO tracing is active. This should guarantee reliable traces in the easiest way possible. The current workaround is not reliable on SMP. "Works enough" is what I'm thinking of. Thanks. -- Pekka Paalanen http://www.iki.fi/pq/