Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932112AbXKPLxR (ORCPT ); Fri, 16 Nov 2007 06:53:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756518AbXKPLxF (ORCPT ); Fri, 16 Nov 2007 06:53:05 -0500 Received: from dpc691978010.direcpc.com ([69.19.78.10]:35191 "EHLO third-harmonic.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757302AbXKPLxE (ORCPT ); Fri, 16 Nov 2007 06:53:04 -0500 Message-ID: <473D8560.5060500@third-harmonic.com> Date: Fri, 16 Nov 2007 06:56:16 -0500 From: john cooper User-Agent: Thunderbird 1.5.0.2 (X11/20060420) MIME-Version: 1.0 To: Steven Rostedt CC: Tim Bird , Thomas Gleixner , linux kernel , Ingo Molnar , john cooper Subject: Re: MIPS RT debug support References: <473B8F91.20704@am.sony.com> <473BADD4.5030400@third-harmonic.com> <473CD6E1.1060607@am.sony.com> <473CF8A5.9030101@third-harmonic.com> In-Reply-To: Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1340 Lines: 34 Steven Rostedt wrote: > IIRC, only CALLER_ADDR0 is actually used (I've found that the others are > mostly unreliable). I seem to recall more use was made of __builtin_return_address(n) for 0 < n in the past compared to the current code. Likely for shallow frames the 0 < n calls were potentially returning invalid data which is why they currently appear to be commented out. Rather than lobbying to fix __builtin_return_address(), replacing it with a primitive which works in all cases seems an easier solution. That stub stack frame really does provide useful debug information. In the case of ARM I simply walked the stack. Worst case in that vintage of the code was four iterations so the overhead was in the noise. That same solution could easily be applied to other architectures. > It's been several years since > I've worked on mips (I'd love to do it again, if someone sends me a box!, > hint hint). Concerning a MIPS board, if no freebies should arrive you might want to dig up a linux footprint friendly version of a Linksys WRT54GS. -john -- john.cooper@third-harmonic.com - 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/