Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750730AbVJNO4K (ORCPT ); Fri, 14 Oct 2005 10:56:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750744AbVJNO4K (ORCPT ); Fri, 14 Oct 2005 10:56:10 -0400 Received: from xproxy.gmail.com ([66.249.82.204]:32612 "EHLO xproxy.gmail.com") by vger.kernel.org with ESMTP id S1750730AbVJNO4I convert rfc822-to-8bit (ORCPT ); Fri, 14 Oct 2005 10:56:08 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=myfbko9BCEXS1qsvaoAt45WDgtuy/A65e1o1k57QVwsy7GHN37jdaHBSVFBz4Sv3E1fFXotN/W09E30dhqqsx8ux/MfvZStNmdGPH2ZN7GzwnwAgbeM+wlMgjTpzVxvWKowtHli3ugc5ARoY/9f0aKiqSfTKVR6d8dAUJwtEXWY= Message-ID: <5bdc1c8b0510140756u1b006de9td552539421666bec@mail.gmail.com> Date: Fri, 14 Oct 2005 07:56:05 -0700 From: Mark Knecht To: Ingo Molnar Subject: Re: 2.6.14-rc4-rt1 - enable IRQ-off tracing causes kernel to fault at boot Cc: Steven Rostedt , linux-kernel@vger.kernel.org In-Reply-To: <20051014035230.GB6513@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Content-Disposition: inline References: <5bdc1c8b0510121000i5db112f2p642f66686fb46c57@mail.gmail.com> <20051013073029.GA12801@elte.hu> <5bdc1c8b0510130526k6064c640pecded9ccb0ef7dde@mail.gmail.com> <5bdc1c8b0510131210i64f7f289q557368b056e59e18@mail.gmail.com> <20051014035230.GB6513@elte.hu> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2939 Lines: 67 On 10/13/05, Ingo Molnar wrote: > > * Mark Knecht wrote: > > > Ingo & Steve, > > Thank you for your great instructions that even a guitar player > > could basically follow. After about an hour of messing around I did > > manage to capture the crash. The console file is attached. > > > > NOTE: The first time I booted the kernel it got to the crash point and > > the machine rebooted. The second time it booted I got the trace. Both > > boots are in the capture file. > > thanks, this log is much more informative. No smoking gun though, but it > seems something fundamental (probably lowlevel x64 code) has been broken > by -rt1. > > Do the crashes go away if you take the -rc3-rt13 version of > arch/x86_64/kernel/entry.S and copy it over into the -rc4-rt1 tree? > [this undoes a particular set of CONFIG_CRITICAL_IRQSOFF_TIMING fixes > from the x64 code, which i did during -rc3-rt13 => -rc4-rt1] Indeed it is fixed by doing this. Options are on but the modified kernel does boot: ***************************************************************************** * * * REMINDER, the following debugging options are turned on in your .config: * * * * CONFIG_DEBUG_PREEMPT * * CONFIG_CRITICAL_PREEMPT_TIMING * * CONFIG_CRITICAL_IRQSOFF_TIMING * * * * they may increase runtime overhead and latencies. * * * ***************************************************************************** mark@lightning ~ $ uname -a Linux lightning 2.6.14-rc4-rt1 #8 PREEMPT Fri Oct 14 07:46:29 PDT 2005 x86_64 AMD Athlon(tm) 64 Processor 3000+ AuthenticAMD GNU/Linux mark@lightning ~ $ > > (Note that doing this will re-introduce tracing bugs, which can result > in false-positive latency readings - but it should fix any related > lowlevel bug in the assembly code.) > > if this indeed solves the crash then i'd suggest to restore the -rt1 > version of entry.S, and i'd suggest to disable CRITICAL_IRQSOFF_TIMING > until i fix it. You should be able to get pretty good latency tracing > info even without CRITICAL_IRQSOFF_TIMING. > > Ingo > Will got back to the original entry.S file with the IRQoff option turned off. Let me know when you have a fix to test, or if you need more data. Thanks, Mark - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/