Re: [Qemu-devel] SCSI CD-ROM hotplug problem

[Paolo Bonzini <pbonzini@redhat.com>]

Il 25/04/2013 15:40, Liuji (Jeremy) ha scritto:
> Hello, everyone
> 
> I have a question about hotplug of cd-rom.
> 
> version of qemu: Apr-22-2013   bb71623811686ce3c34ce724f073f5c5dd95f51b
> 
> 1) start the vm:
> qemu-kvm -enable-kvm -m 1024 -smp 2 -boot c -drive file=/home/vm/winxp.qcow2,if=none,id=drive0,format=qcow2 
> -device virtio-blk-pci,scsi=off,drive=drive0,id=disk0 -monitor stdio -vnc 186.100.8.136:1 
> -device lsi,id=scsi0,bus=pci.0
> 
> 2) use "drive_add" and "device_add" commands to hotplug a cd-rom:
> (qemu) drive_add 0 file=/home/vm/aaa.iso,if=none,id=my-cdrom-drive,readonly=on,format=raw
> (qemu) device_add scsi-cd,bus=scsi0.0,scsi-id=2,drive=my-cdrom-drive,id=my-cdrom
> 
> 3) but I can't find the new cd-rom in the WindowXP vm.

This is because Windows has not rescanned the SCSI bus.  To force a
rescan, open a command prompt, then type "diskpart" and then "rescan".

> 4) and then, I use "pci_add" command to hotplug another cd-rom:
> (qemu) pci_add auto storage file=/home/vm/bbb.iso,if=scsi,readonly=on,format=raw,media=cdrom

This works because it adds an entirely new SCSI controller.

> 5) I not only found the second cd-rom, but also found first cd-rom in the WindowXP vm.

This is probably some oddity of Windows, which forces a rescan of all
SCSI buses when a new controller is hot-plugged---or something like that.

Paolo