[pve-devel] [PATCH qemu-server 18/31] blockdev: add change_medium() helper

[Fabian Grünbichler]

> DERUMIER, Alexandre via pve-devel <pve-devel at lists.proxmox.com> hat am 01.07.2025 09:30 CEST geschrieben:
> Another thing, 
> 
> if the vm is start with cdrom=none,  then you switch to an iso,
> 
> the throttle group is not generated (+the autogenerated nodenames)

if you start a VM with cdrom=none, throttle group object is generated:

# qm config 123
boot: order=ide2;ide0
ide0: cdrom,media=cdrom
ide2: none,media=cdrom
kvm: 0
meta: creation-qemu=10.0.2,ctime=1750423164
scsi0: local:123/vm-123-disk-1.raw,size=1G
smbios1: uuid=8ca437bc-4a11-4bf2-8a5d-61d5cf407670
vmgenid: 0ca5ca77-a0d8-4f32-a7c3-c3c752f0280e

# qom-list /objects
type (string)
throttle-drive-ide2 (child<throttle-group>)
throttle-drive-ide0 (child<throttle-group>)
pc.ram (child<memory-backend-ram>)
throttle-drive-scsi0 (child<throttle-group>)

and switching that CD drom drive to using the host drive or an iso volume fails:

Parameter verification failed. (400)

ide0: hotplug problem - VM 123 qmp command 'object-add' failed - attempt to add duplicate property 'throttle-drive-ide0' to object (type 'container')

switching ide0 to none while running removes the object, and then switching back to cdrom works, and the block nodes also look okay.

for me, switching from cdrom to none to an iso file works correctly.
starting the VM with iso volume attached and switching to either none or a different iso file also work correctly.

@alexandre are you testing with all three patch series applied (qemu-server, pve-qemu-kvm, pve-storage)?