Forwarding to linux-kernel. I code, therefore I am --- On Sat, 10/30/10, Alex Davis <alex14641@xxxxxxxxx> wrote: > From: Alex Davis <alex14641@xxxxxxxxx> > Subject: Re: CD-ROM size not updated when switching CD-ROM images. > To: "David Ahern" <dsahern@xxxxxxxxx> > Cc: "Stefan Hajnoczi" <stefanha@xxxxxxxxx>, kvm@xxxxxxxxxxxxxxx > Date: Saturday, October 30, 2010, 4:32 PM > > > --- 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
