We keep port 0 reserved for compat with older guests, where only
virtio-console was expected. Even if a system is started without a
virtio-console port, port #0 is kept aside. However, after a
virtconsole port is unplugged, port id 0 became available, and the next
hotplug of a virtserialport caused failure due to it not being a console
port.
Steps to reproduce:
$ ./x86_64-softmmu/qemu-system-x86_64 -m 512 -cpu host -enable-kvm -device virtio-serial-pci -monitor stdio -vnc :1
QEMU 2.0.91 monitor - type 'help' for more information
(qemu) device_add virtconsole,id=p1
(qemu) device_del p1
(qemu) device_add virtserialport,id=p1
Port number 0 on virtio-serial devices reserved for virtconsole devices for backward compatibility.
Device 'virtserialport' could not be initialized
(qemu) quit
Reported-by: dengmin <mdeng@redhat.com>
Reviewed-by: Amos Kong <akong@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
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