From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:43376) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RDAC4-0002ve-Fd for qemu-devel@nongnu.org; Mon, 10 Oct 2011 03:22:37 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RDAC3-0007de-3o for qemu-devel@nongnu.org; Mon, 10 Oct 2011 03:22:36 -0400 Received: from fmmailgate02.web.de ([217.72.192.227]:46080) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RDAC2-0007dZ-OH for qemu-devel@nongnu.org; Mon, 10 Oct 2011 03:22:35 -0400 Message-ID: <4E929D38.5050008@web.de> Date: Mon, 10 Oct 2011 09:22:32 +0200 From: Jan Kiszka 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> <4E9297CB.8010303@cn.fujitsu.com> <4E929848.6030105@web.de> <4E929BFC.20406@cn.fujitsu.com> In-Reply-To: <4E929BFC.20406@cn.fujitsu.com> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig4DF3E07670DE59C337C4CBE8" Sender: jan.kiszka@web.de 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: Wen Congyang Cc: Luiz Capitulino , "Richard W.M. Jones" , qemu-devel This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig4DF3E07670DE59C337C4CBE8 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable On 2011-10-10 09:17, Wen Congyang wrote: > At 10/10/2011 03:01 PM, Jan Kiszka Write: >> On 2011-10-10 08:59, Wen Congyang wrote: >>> At 10/10/2011 02:52 PM, Jan Kiszka Write: >>>> On 2011-10-10 04:21, Wen Congyang wrote: >>>>> At 10/09/2011 06:23 PM, Richard W.M. Jones Write: >>>>>> On Sun, Oct 09, 2011 at 10:49:57AM +0200, Jan Kiszka wrote: >>>>>>> As explained in the other replies: It is way more future-proof to= use an >>>>>>> interface for this which was designed for it (remote gdb) instead= of >>>>>>> artificially relaxing reasonable constraints of the migration mec= hanism >>>>>>> plus having to follow that format with the post-processing tool. >>>>>> >>>>>> Any interface that isn't "get this information off my production >>>>>> server *now*" so that I can get the server restarted, and send it = to >>>>>> an expert to analyse -- is a poor interface, whether it was design= ed >>>>>> like that or not. Perhaps we don't have the right interface at al= l, >>>>>> but remote gdb is not it. >>>>> >>>>> What about the following idea? >>>>> >>>>> Introduce a new monitor command named dump, and this command accept= s a filename. >>>>> We can use almost all migration's code. We use this command to dump= guest's >>>>> memory, so there is no need to check whether the guest has a unmigr= atable device. >>>> >>>> I do not want to reject this proposal categorically, but I would lik= e to >>>> see the gdb path fail /wrt essential requirements first. So far I do= n't >>>> see it would. >>> >>> =91gdb path fail /wrt essential requirements=92 >>> >>> what does it mean? >> >> That you explain why reading reading memory and processor states via t= he >> remote gdb interface and dumping it into a proper core file cannot be >> made working for you. >=20 > First, I think crash can not analyze such core file. But it is not very= important. >=20 > What is remote gdb interface? man qemu -> gdb. > Do you mean that: the supporter uses gdb from another machine Or locally. There are various transports possible. > to connect to customer's machine and get the data? If so, this way can = not be > used when the customer needs to dump the guest's memory automatically w= hen watchdog timeouts. It is just another channel that can conceptually be used like the monitor, by a management app like libvirt, directly or indirectly via a scripted gdb frontend, or also by a human who wants to save some ongoing gdb session for later analysis. This dual use make such an approach the preferred one. Jan --------------enig4DF3E07670DE59C337C4CBE8 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.16 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk6SnTgACgkQitSsb3rl5xTn8wCguTBfxqOou0vyuz3f0Qbv8963 BBMAoI9Y2Ex3eJ2GrM0AMdTHAYsziSPC =bxRT -----END PGP SIGNATURE----- --------------enig4DF3E07670DE59C337C4CBE8--