Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754210AbcCYR1f (ORCPT ); Fri, 25 Mar 2016 13:27:35 -0400 Received: from mail-vk0-f44.google.com ([209.85.213.44]:35048 "EHLO mail-vk0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753958AbcCYR1d (ORCPT ); Fri, 25 Mar 2016 13:27:33 -0400 MIME-Version: 1.0 In-Reply-To: References: <20160314235035.GA5799@localhost.localdomain> <1457999823.11972.143.camel@perches.com> <20160315112458.7248d665@canb.auug.org.au> <20160325083621.GA21959@gmail.com> Date: Fri, 25 Mar 2016 11:27:32 -0600 Message-ID: Subject: Re: [GIT PULL v4.6] MDB Linux Kernel Debugger x86/x86_64 From: Jeffrey Merkey To: Ingo Molnar Cc: Stephen Rothwell , Joe Perches , linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, linux-kbuild Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4304 Lines: 129 On 3/25/16, Jeffrey Merkey wrote: > On 3/25/16, Ingo Molnar wrote: >> >> * Stephen Rothwell wrote: >> >>> Hi Joe, >>> >>> On Mon, 14 Mar 2016 16:57:03 -0700 Joe Perches wrote: >>> > >>> > On Mon, 2016-03-14 at 17:50 -0600, Jeffrey Merkey wrote: >>> > > The following changes since commit >>> > > b562e44f507e863c6792946e4e1b1449fbbac85d: >>> > > >>> > > Linux 4.5 (2016-03-13 21:28:54 -0700) >>> > > >>> > > are available in the git repository at: >>> > > >>> > > https://github.com/jeffmerkey/linux.git tags/mdb-v4.5-signed >>> > > >>> > > for you to fetch changes up to >>> > > 2e9c184e1215dca2b4c59c347f40a0986b8e7460: >>> > > >>> > > Add MDB Debugger to linux v4.5 (2016-03-14 15:17:44 -0600) >>> > >>> > If Linus doesn't pull this, Stephen, could you please add this >>> > tree to -next so it has some testing and validation done? >>> >>> Well, I really need a request from the ongoing maintainer and also some >>> indication of which kernel release (if any) it is likely to be merged >>> into ... >> >> So neither the x86 nor other affected maintainers have acked these >> changes >> or have >> agreed to merge it - in fact there are outstanding NAKs against this >> tree, >> which >> were not mentioned in the pull request. >> >> Here's one of the objections by me: >> >> https://lkml.org/lkml/2016/1/29/64 >> >> ... which technical objections were replied to by Jeff Merkey by accusing >> me >> of >> trolling: >> >> "You were not included on the post since you are not a maintainer of >> watchdog.c >> so I am confused as to why you are nacking and trolling me on >> something >> not in >> your area." >> >> https://lkml.org/lkml/2016/1/29/397 >> >> So this tree is very far from being ready and I'm not convinced we want >> to >> merge >> it in its current form. If we merge bits of it then we want to merge it >> via >> the >> x86 tree, not a separate tree. >> >> In fact I also have more fundamental objections as well, such as the >> question of >> unnecessary code duplication: this new MDB debugger overlaps in >> functionality with >> the already in-tree kgdb+KDB live kernel debugger approach: >> >> I don't think we want to see two overlapping solutions in this area, both >> of >> which >> are inferior in their own ways. If then the KDB frontend should be >> improved: >> >> features such as disassembler output, more commands and usability >> improvements >> that can and should be added to the KDB front-end instead. I see nothing >> in >> this >> patch that couldn't be added to KDB/KGDB. >> >> All in one, I'd much rather like to see a gradual set of improvement >> patches >> to >> KDB, to improve live kernel debugging, than this kind of monolithic, arch >> dependent duplication of functionality. >> >> Thanks, >> >> Ingo >> > > Hi Ingo, > > Adding the disassembler to kgb/kgdb would not be all that > straightforward. the architecture of kgdb/kdb does not support it -- > it would be significant rewrite of kdb -- in fact, it would have to be > completely restructured . There are also as you point out some > patches in the debugger you nacked. but removing these is easy. > > I also would have to go to whomever is maintaining kdb and to be > honest, I am not all that interested in doing a bunch of work only to > have it rejected or ignored, so the "bait and switch" game of saying > "Please do X for us and we'll think about adding Y" isn't something I > am going to waste my time on. Linux has more than one file system, > more than one ethernet card driver, so there is no reason it can have > more than one debugger. > > Kdb locks up a lot due to the design of it's smp roundup code for > stoping processors, it's a different design totally. > > If you want me to do these things I would need free reign and to be > honest, kdb is nowhere near as complete as mdb is. > > All that being said if you want me to do as you ask then you need to > show me that you are serious about taking work I do for these areas. > > Jeff In simple terms if you pull mdb as a branch to the x86 tree then I will do whatever you ask me to do to integrate it into kdb. You have to accept the code as is to show me you are serious, then I will adapt it however you ask me to. Jeff