From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:58763) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RH9t9-00033m-8A for qemu-devel@nongnu.org; Fri, 21 Oct 2011 03:51:36 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RH9t7-0000fW-OY for qemu-devel@nongnu.org; Fri, 21 Oct 2011 03:51:35 -0400 Received: from [222.73.24.84] (port=52268 helo=song.cn.fujitsu.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RH9qj-0000Mr-9v for qemu-devel@nongnu.org; Fri, 21 Oct 2011 03:51:33 -0400 Message-ID: <4EA1244C.4020006@cn.fujitsu.com> Date: Fri, 21 Oct 2011 15:50:36 +0800 From: Wen Congyang MIME-Version: 1.0 References: <4E8ECA91.8040409@cn.fujitsu.com> <4E8ED167.1000705@siemens.com> <20111008151622.GA17181@amd.home.annexia.org> <4E916035.5050906@web.de> <20111009102338.GN16799@amd.home.annexia.org> <4E92568E.2010507@cn.fujitsu.com> <4E929618.4040403@web.de> <20111010090246.GF9408@redhat.com> <4E92BC11.3030508@siemens.com> <4E9D2791.5070207@cn.fujitsu.com> <4E9D3059.7050903@siemens.com> <4E9D31B4.1010000@cn.fujitsu.com> <4E9D3678.3010904@siemens.com> <4E9D3804.5040000@cn.fujitsu.com> <4E9D3847.8040202@siemens.com> <4E9D3965.4090003@cn.fujitsu.com> <4E9D394E.6050907@siemens.com> <20111019110401.b77f79fa.kamezawa.hiroyu@jp.fujitsu.com> <4E9EB72B.6010903@siemens.com> <4E9F77BE.50701@cn.fujitsu.com> <4E9FECE5.2000802@siemens.com> <4E9FF1F7.7070104@cn.fujitsu.com> <4EA11B18.8080908@siemens.com> In-Reply-To: <4EA11B18.8080908@siemens.com> Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1 Subject: Re: [Qemu-devel] [Question] dump memory when host pci device is used by guest List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jan Kiszka Cc: Luiz Capitulino , Dave Anderson , qemu-devel , KAMEZAWA Hiroyuki , "Richard W.M. Jones" At 10/21/2011 03:11 PM, Jan Kiszka Write: > On 2011-10-20 12:03, Wen Congyang wrote: >> At 10/20/2011 05:41 PM, Jan Kiszka Write: >>> On 2011-10-20 03:22, Wen Congyang wrote: >>>>>> I didn't read full story but 'crash' is used for investigating kernel core generated >>>>>> by kdump for several years. Considering support service guys, virsh dump should support >>>>>> a format for crash because they can't work well at investigating vmcore by gdb. >>>>>> >>>>>> crash has several functionality useful for them as 'show kerne log', 'focus on a cpu' >>>>>> 'for-each-task', 'for-each-vma', 'extract ftrace log' etc. >>>>>> >>>>>> Anyway, if a man, who is not developper of qemu/kvm, should learn 2 tools for >>>>>> investigating kernel dump, it sounds harmful. >>>>> >>>>> Right, that's why everything (live debugging & crash analysis) should be >>>>> consolidated on the long run over gdb. crash is architecturally obsolete >>>>> today - not saying it is useless! >>>> >>>> I do not know why crash is obsoleted today. Is there a new better tool to instead >>>> crash? >>> >>> I'm not aware of equally powerful (python) scripts for gdb as >>> replacement, but I think it's worth starting a porting effort at some point. >>> >>>> >>>> At least, I always use crash to live debugging & crash analysis. >>> >>> Then you may answer some questions to me: >>> - Can you attach to a remote target (kgdb, qemu, etc.) and how? >> >> No. crash's live debugging only can work the kernel is live. I can use it get >> some var's value, or some other information from kernel. If kernel panics, >> we can use gdb to attach to a remote target as you said. But on end user machine, >> we can not do it, we should dump the memory into a file and analyze it in another >> machine while the end user's guest can be restart. >> >>> - Can you use it with latest gdb versions or is the gdb functionality >>> hard-wired due to an embedded gdb core in crash (that's how I >>> understood Christoph's reply to this topic) >> >> If I use crash, I can not use latest gdb versions. Do we always need to use >> the latest gdb versions? Currently, gdb-7.0 is embedded into crash, and it >> is enough to me. If the gdb embedded into crash cannot anaylze the vmcore, I >> think we can update it and rebuild crash. > > crash is simply designed the wrong way around (from today's > perspective): it should augment upstream gdb instead of forking it. Cc Dave Anderson. He knows how crash uses gdb. I think that crash does not fork a task to execute gdb, and gdb is a part of crash. Thanks Wen Congyang > > Jan >