From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263119AbUB0VMw (ORCPT ); Fri, 27 Feb 2004 16:12:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263136AbUB0VMw (ORCPT ); Fri, 27 Feb 2004 16:12:52 -0500 Received: from adsl-216-103-111-100.dsl.snfc21.pacbell.net ([216.103.111.100]:36754 "EHLO www.piet.net") by vger.kernel.org with ESMTP id S263119AbUB0VKq (ORCPT ); Fri, 27 Feb 2004 16:10:46 -0500 Subject: Re: kgdb support in vanilla 2.6.2 From: Piet Delaney To: George Anzinger Cc: Andi Kleen , "Amit S. Kale" , akpm@osdl.org, pavel@ucw.cz, linux-kernel@vger.kernel.org, piggy@timesys.com, trini@kernel.crashing.org, piet In-Reply-To: <40295388.5080901@mvista.com> References: <20040204230133.GA8702@elf.ucw.cz.suse.lists.linux.kernel> <20040204155452.4 9c1eba8.akpm@osdl.org.suse.lists.linux.kernel> <200402052320.04393.amitkale@emsyssoft.com> <20040206032054.3fd7db8d.ak@suse.de> <40295388.5080901@mvista.com> Content-Type: text/plain Content-Transfer-Encoding: 7bit X-Mailer: Ximian Evolution 1.0.8 (1.0.8-10) Date: 27 Feb 2004 13:09:11 -0800 Message-Id: <1077916151.3291.133.camel@www.piet.net> Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2004-02-10 at 13:56, George Anzinger wrote: I thought I'd poke around an AMD64 with etherbased kgdb on 2.6.*. I just picked up a used AMD64 K8D Master-F MS-9131 and thought I'd install Fedora Core 1 test1 and the latest kernel from kernel.org. It Might be interesting to try out a SuSE release also, I was wondering if 9.0 from linuxiso.org might be best. Last I worked with your kgdb patch for 2.6 Andrew's mm patch had the latest code; Is that still the case? -piet > Andi Kleen wrote: > > On Thu, 5 Feb 2004 23:20:04 +0530 > > "Amit S. Kale" wrote: > > > > > >>On Thursday 05 Feb 2004 8:41 am, Andi Kleen wrote: > >> > >>>Andrew Morton writes: > >>> > >>>>need to take a look at such things and really convice ourselves that > >>>>they're worthwhile. Personally, I'd only be interested in the basic > >>>>stub. > >>> > >>>What I found always extremly ugly in the i386 stub was that it uses > >>>magic globals to talk to the page fault handler. For the x86-64 > >>>version I replaced that by just using __get/__put_user in the memory > >>>accesses, which is much cleaner. I would suggest doing that for i386 > >>>too. > >> > >>May be I am missing something obvious. When debugging a page fault handler if > >>kgdb accesses an swapped-out user page doesn't it deadlock when trying to > >>hold mm semaphore? > > > > > > Modern i386 kernels don't grab the mm semaphore when the access is >= TASK_SIZE > > and the access came from kernel space (actually I see x86-64 still does, but that's > > a bug, will fix). You could only see a deadlock when using user addresses > > and you already hold the mm semaphore for writing (normal read lock is ok). > > Just don't do that. > > > > > > > >>George has coded cfi directives i386 too. He can use them to backtrace past > >>irqs stack. > > > > > > Problem is that he did it without binutils support. I don't think that's a good > > idea because it makes the code basically unmaintainable for normal souls > > (it's like writing assembly code directly in hex) > > Well, bin utils, at this time, makes it even worse in that it does not support > the expression syntax. Also, it is not asm but dwarf2 and it is written in, > IMHO, useful macros (not hex :) > > > > -- > George Anzinger george@mvista.com > High-res-timers: http://sourceforge.net/projects/high-res-timers/ > Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml > > - > 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/ -- piet@www.piet.net