From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Davis Subject: Re: CD-ROM size not updated when switching CD-ROM images. Date: Sat, 30 Oct 2010 13:32:19 -0700 (PDT) Message-ID: <147014.52223.qm@web50203.mail.re2.yahoo.com> References: <4CBF1C5F.1070406@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Stefan Hajnoczi , kvm@vger.kernel.org To: David Ahern Return-path: Received: from nm8-vm0.bullet.mail.ac4.yahoo.com ([98.139.52.230]:31126 "HELO nm8-vm0.bullet.mail.ac4.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751105Ab0J3UcV (ORCPT ); Sat, 30 Oct 2010 16:32:21 -0400 In-Reply-To: <4CBF1C5F.1070406@gmail.com> Sender: kvm-owner@vger.kernel.org List-ID: --- On Wed, 10/20/10, David Ahern wrote: > From: David Ahern > Subject: Re: CD-ROM size not updated when switching CD-ROM images. > To: "Alex Davis" > Cc: "Stefan Hajnoczi" , kvm@vger.kernel.org > Date: Wednesday, October 20, 2010, 12:44 PM > > > On 10/19/10 18:03, Alex Davis wrote: > > >> You ejected the CD-ROM on the QEMU side, the guest > doesn't > >> necessarily > >> know about the medium change. What happens > when you > >> use "eject > >> /dev/sr0" inside the guest instead? > > I get a 'no medium found' error from the 'dd..' > command. After > > going into the the monitor, ejecting and reloading the > disk, > > I still get the size of the first disk in the guest. > > As I recall the old data is coming from the host page > cache; it is not > seeing the media change. Try dropping the cache in the host > on a media > change (echo 3 > /proc/sys/vm/drop_caches) or modify > qemu to close and > reopen the cdrom device. > > David I am able to reproduce this problem with just a plain kernel using the ata_piix driver, an initrd that just starts a shell, and plain qemu. When the disk is changed via the monitor, the guest invokes the error- handling code on the next read of the CD-ROM, but the code path doesn't trigger the 'update size' logic. I did an experiment where I placed the line 'sdev->changed = 1' in the sr_open method in sr.c of the guest kernel source, the size was updated, but I will look to see if there's something in qemu that can be changed to make it work properly. Of course any input from the qemu/kvm developers is appreciated. I code, therefore I am > > >> > >> I don't know how CD-ROM media change works on > real > >> hardware, but that > >> is the behavior that QEMU should be following. > >> > >> Stefan > > > > > > > > -- > > To unsubscribe from this list: send the line > "unsubscribe kvm" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > >