From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39322) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V5BoS-0003P6-42 for qemu-devel@nongnu.org; Fri, 02 Aug 2013 05:38:27 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1V5BoO-0000oJ-4X for qemu-devel@nongnu.org; Fri, 02 Aug 2013 05:38:19 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47275) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V5BbQ-0004kB-Lx for qemu-devel@nongnu.org; Fri, 02 Aug 2013 05:24:52 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r729OpKx025200 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Fri, 2 Aug 2013 05:24:51 -0400 Date: Fri, 2 Aug 2013 10:24:48 +0100 From: "Daniel P. Berrange" Message-ID: <20130802092448.GA25831@redhat.com> References: <1375362537.4891.28.camel@localhost.localdomain> <51FA6E34.5000404@redhat.com> <51FA8C4D.70308@redhat.com> <51FADFEB.1080804@redhat.com> <51FAE445.3020607@redhat.com> <51FB6E4F.4010107@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <51FB6E4F.4010107@redhat.com> Subject: Re: [Qemu-devel] pvpanic device should not be automatically included as an internal device Reply-To: "Daniel P. Berrange" List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: libvir-list@redhat.com, qemu-devel@nongnu.org On Fri, Aug 02, 2013 at 10:31:11AM +0200, Paolo Bonzini wrote: > On 08/02/2013 12:42 AM, Eric Blake wrote: > >On 08/01/2013 04:23 PM, Paolo Bonzini wrote: > >>>Automatic devices with no command line argument have proven to be a > >>>nightmare for libvirt as well. Although the just-released libvirt 1.1.1 > >>>now supports the element for controlling the command line > >>>parameters of qemu related to how qemu will behave when the pvpanic > >>>device is triggered, I would also welcome having the ability to control > >>>whether the guest even has a pvpanic device exposed, just as we can > >>>control whether a guest has a memballoon device exposed. > >> > >>This is quite different from memballoon. > >> > >>pvpanic is a single I/O port, it doesn't use up a PCI slot (thus > >>causing conflicts with other devices at the same address). > >> > >>Perhaps this issue is simply fixed by making the _STA method > >>return 0x0B instead of 0x0F (i.e. turning off the "show in user > >>interface" bit). > > > >That may "fix" the issue of a windows guest showing the yellow ! mark, > >but what if, down the road, someone writes an actual windows driver that > >is aware of that port and how to make a windows BSOD write a panic > >notification to the port? How does a user go about installing such a > >driver if the device is not exposed in the user interface list of devices? > > The user can still manually install a driver even for a device that > is not exposed. > > Having to manually specify the pvpanic device would be yet another > knob that nobody uses. Panic notification is a useful feature that > should be supported with no particular intervention from the user. Yep, that was the big motivation behind doing it as an I/O port that we could have enabled by default, as opposed to a virtio serial device or some other paravirt device that required explicit configuration. Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|