From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MQol4-0005jS-2A for qemu-devel@nongnu.org; Tue, 14 Jul 2009 16:37:50 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MQoky-0005fb-Qd for qemu-devel@nongnu.org; Tue, 14 Jul 2009 16:37:48 -0400 Received: from [199.232.76.173] (port=37621 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MQoky-0005fY-L7 for qemu-devel@nongnu.org; Tue, 14 Jul 2009 16:37:44 -0400 Received: from fmmailgate02.web.de ([217.72.192.227]:52506) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1MQoky-0008DD-0y for qemu-devel@nongnu.org; Tue, 14 Jul 2009 16:37:44 -0400 Message-ID: <4A5CEC8E.6030200@web.de> Date: Tue, 14 Jul 2009 22:37:34 +0200 From: Jan Kiszka MIME-Version: 1.0 References: <4A5C3FBB.10306@siemens.com> <4A5C9EDF.3060705@codemonkey.ws> <200907142030.27019.paul@codesourcery.com> <4A5CE4AB.3090708@us.ibm.com> In-Reply-To: <4A5CE4AB.3090708@us.ibm.com> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigF1358030AC8F70DF809846E0" Sender: jan.kiszka@web.de Subject: [Qemu-devel] Re: [PATCH] monitor: Add port write command List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: Paul Brook , qemu-devel@nongnu.org This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigF1358030AC8F70DF809846E0 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: quoted-printable Anthony Liguori wrote: > Paul Brook wrote: >>> What would be really cool about this change is that we could introduc= e a >>> new set of commands to manipulate device state. We could save/restor= e >>> individual device state and that would allow us to dump device state = via >>> the monitor and to manipulate individual fields of the device state. = I >>> think this could be pretty useful for debugging. >>> =20 >> >> I'd be reluctant to expose the savevm state to the user. >> >> For debugging qemu I don't see it providing any real benefit over >> firing up GDB and poking directly at the device directly. >> >> For debugging the guest there is some argument for exposing the device= >> state (preferably via the gdb stub). However I think the savevm data >> tends to expose too many internal implementation details, >=20 > That sounds like an issue with the devices. >=20 > The savevm state should not contain internal implementation details as > that makes backwards compatibility hard to maintain. I think for a > large class of devices, the savevm state almost perfectly matches the > device register state and having a nice interface to that seems like a > useful thing. >=20 I agree that most (but maybe not all) of the saved device states consist of register or register-like states that could nicely be presented to the user or even manipulated. To avoid illicit manipulations, we could add stricter test to loadvm handlers or define valid ranges of the fields. Or we could even mark certain fields as read-only or even internal (ie. hidden). In any case, such an interface would be a great improvement over having to debug qemu itself! If you are unfamiliar with the qemu design, this is surely no straightforward method for obtaining information about the virtual device states... Will see if I or some colleague can contribute to this effort. Jan --------------enigF1358030AC8F70DF809846E0 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (GNU/Linux) Comment: Using GnuPG with SUSE - http://enigmail.mozdev.org iEYEARECAAYFAkpc7JQACgkQniDOoMHTA+kfhgCeN8U/0ljJU+ZfAjKV+oOmNYmG +PAAnR89kz17OEMD9mHTgxs1xDvlXaT0 =Yrbk -----END PGP SIGNATURE----- --------------enigF1358030AC8F70DF809846E0--