--- On Wed, 10/20/10, David Ahern <dsahern@xxxxxxxxx> wrote: > From: David Ahern <dsahern@xxxxxxxxx> > Subject: Re: CD-ROM size not updated when switching CD-ROM images. > To: "Alex Davis" <alex14641@xxxxxxxxx> > Cc: "Stefan Hajnoczi" <stefanha@xxxxxxxxx>, kvm@xxxxxxxxxxxxxxx > 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@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
