We may be saying the same thing, but I'd word it differently.  If a
 "device" has a "path" then it gets a se->compat (compatibility?) record.
   -  Within that record each device gets an instance_id value based on its
name.  Multiple IDs for the same name are allowed.
   -  At the "se" level each device also gets an instance id but now based
on path + name.  There can only be one instance for that combination which
requires that the path must be unique for each device name.

In this case both SCSI device have the path "0:0:0" (chan:id:lun) which
violates the above requirement.

Looking at the debug info I noticed that for "virtio-net" the (PCI) path is
not all zeroes (0000:00:01.0).  Makes me wonder if maybe something on the
SCSI side of things should be generating valid paths.

Still digging.

On 1 July 2016 at 09:08, Dr. David Alan Gilbert <email address hidden> wrote:

> Yeh I *think* the idea is that you either:
>      a) have an instance_id
> or
>      b) have a unique name
>          in which case you're also allowed to have an old compatibility
> name/instance_id to work with old code that didn't have a unique name
> (that's in se->compat)
>
> so the assert is:
>        assert(!se->compat || se->instance_id == 0);
>
>  The !se->compat              corresponds to (a)
>      se->instance_id == 0     corresponds to (b)
>
> Having a unique name is a very good idea for hotplug - it lets you
> unplug the middle one and still receive a migration correctly.
>
> Dave
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1594239
>
> Title:
>   After adding more scsi disks for Aarch64 virtual machine, start the VM
>   and got Qemu Error
>
> Status in QEMU:
>   Confirmed
>
> Bug description:
>   Description
>   ===========
>   Using virt-manager to create a VM in Aarch64, Ubuntu 16.04.
>   Add scsi disk to the VM. After add four or more scsi disks, start the VM
> and will got Qemu error.
>
>   Steps to reproduce
>   ==================
>   1.Use virt-manager to create a VM.
>   2.After the VM is started, add scsi disk to the VM. They will be
> allocated to "sdb,sdc,sdd....." .
>   3.If we got a disk name > sdg, virt-manager will also assign a
> virtio-scsi controller for this disk.And the VM will be shutdown.
>   4.Start the VM, will see the error log.
>
>
>   Expected result
>   ===============
>   Start the vm smoothly.The added disks can work.
>
>   Actual result
>   =============
>   Got the error:
>   starting domain: internal error: process exited while connecting to
> monitor: qemu-system-aarch64:
> /build/qemu-zxCwKP/qemu-2.5+dfsg/migration/savevm.c:620:
> vmstate_register_with_alias_id: Assertion `!se->compat || se->instance_id
> == 0' failed.
>   details=Traceback (most recent call last):
>     File "/usr/share/virt-manager/virtManager/asyncjob.py", line 90, in
> cb_wrapper
>       callback(asyncjob, *args, **kwargs)
>     File "/usr/share/virt-manager/virtManager/asyncjob.py", line 126, in
> tmpcb
>       callback(*args, **kwargs)
>     File "/usr/share/virt-manager/virtManager/libvirtobject.py", line 83,
> in newfn
>       ret = fn(self, *args, **kwargs)
>     File "/usr/share/virt-manager/virtManager/domain.py", line 1402, in
> startup
>       self._backend.create()
>     File "/usr/local/lib/python2.7/dist-packages/libvirt.py", line 1035,
> in create
>       if ret == -1: raise libvirtError ('virDomainCreate() failed',
> dom=self)
>   libvirtError: internal error: process exited while connecting to
> monitor: qemu-system-aarch64:
> /build/qemu-zxCwKP/qemu-2.5+dfsg/migration/savevm.c:620:
> vmstate_register_with_alias_id: Assertion `!se->compat || se->instance_id
> == 0' failed.
>
>
>   Environment
>   ===========
>   1. virt-manager version is 1.3.2
>
>   2. Which hypervisor did you use?
>       Libvirt+KVM
>       $ kvm --version
>       QEMU emulator version 2.5.0 (Debian 1:2.5+dfsg-5ubuntu10.1),
> Copyright (c) 2003-2008 Fabrice Bellard
>       $ libvirtd --version
>       libvirtd (libvirt) 1.3.1
>
>   3. Which storage type did you use?
>      In the host file system,all in one physics machine.
>   stack@u202154:/opt/stack/nova$ df -hl
>   Filesystem Size Used Avail Use% Mounted on
>   udev 7.8G 0 7.8G 0% /dev
>   tmpfs 1.6G 61M 1.6G 4% /run
>   /dev/sda2 917G 41G 830G 5% /
>   tmpfs 7.9G 0 7.9G 0% /dev/shm
>   tmpfs 5.0M 0 5.0M 0% /run/lock
>   tmpfs 7.9G 0 7.9G 0% /sys/fs/cgroup
>   /dev/sda1 511M 888K 511M 1% /boot/efi
>   cgmfs 100K 0 100K 0% /run/cgmanager/fs
>   tmpfs 1.6G 0 1.6G 0% /run/user/1002
>   tmpfs 1.6G 0 1.6G 0% /run/user/1000
>   tmpfs 1.6G 0 1.6G 0% /run/user/0
>
>   4. Environment information:
>      Architecture : AARCH64
>      OS: Ubuntu 16.04
>
>   The Qemu commmand of libvirt is :
>   2016-06-20 02:39:46.561+0000: starting up libvirt version: 1.3.1,
> package: 1ubuntu10 (William Grant <email address hidden> Fri, 15 Apr 2016
> 12:08:21 +1000), qemu version: 2.5.0 (Debian 1:2.5+dfsg-5ubuntu10.1),
> hostname: u202154
>   LC_ALL=C
> PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
> QEMU_AUDIO_DRV=none /usr/bin/kvm -name cent7 -S -machine
> virt,accel=kvm,usb=off -cpu host -drive
> file=/usr/share/edk2.git/aarch64/QEMU_EFI-pflash.raw,if=pflash,format=raw,unit=0,readonly=on
> -drive
> file=/var/lib/libvirt/qemu/nvram/cent7_VARS.fd,if=pflash,format=raw,unit=1
> -m 2048 -realtime mlock=off -smp 2,sockets=2,cores=1,threads=1 -uuid
> d5462bb6-159e-4dbd-9266-bf8c07fa1695 -nographic -no-user-config -nodefaults
> -chardev
> socket,id=charmonitor,path=/var/lib/libvirt/qemu/domain-cent7/monitor.sock,server,nowait
> -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown
> -boot strict=on -device i82801b11-bridge,id=pci.1,bus=pcie.0,addr=0x1
> -device pci-bridge,chassis_nr=2,id=pci.2,bus=pci.1,addr=0x1 -device
> virtio-scsi-device,id=scsi0 -device lsi,id=scsi1 -device lsi,id=scsi2
> -device virtio-scsi-device,id=scsi3 -usb -drive
> file=/var/lib/libvirt/images/cent7-2.img,format=qcow2,if=none,id=drive-scsi0-0-0-0
> -device
> scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,lun=0,drive=drive-scsi0-0-0-0,id=scsi0-0-0-0,bootindex=1
> -drive if=none,id=drive-scsi0-0-0-1,readonly=on -device
> scsi-cd,bus=scsi0.0,channel=0,scsi-id=0,lun=1,drive=drive-scsi0-0-0-1,id=scsi0-0-0-1
> -drive
> file=/var/lib/libvirt/images/cent7-10.img,format=qcow2,if=none,id=drive-scsi0-0-0-2
> -device
> scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,lun=2,drive=drive-scsi0-0-0-2,id=scsi0-0-0-2
> -drive
> file=/var/lib/libvirt/images/cent7-11.img,format=qcow2,if=none,id=drive-scsi0-0-0-3
> -device
> scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,lun=3,drive=drive-scsi0-0-0-3,id=scsi0-0-0-3
> -drive
> file=/var/lib/libvirt/images/cent7-13.img,format=qcow2,if=none,id=drive-scsi3-0-0-0
> -device
> scsi-hd,bus=scsi3.0,channel=0,scsi-id=0,lun=0,drive=drive-scsi3-0-0-0,id=scsi3-0-0-0
> -netdev tap,fd=33,id=hostnet0,vhost=on,vhostfd=35 -device
> virtio-net-device,netdev=hostnet0,id=net0,mac=52:54:00:a1:6e:75 -serial pty
> -msg timestamp=on
>   Domain id=11 is tainted: host-cpu
>
>   The libvirt xml is:
>   <domain type='kvm'>
>     <name>cent7</name>
>     <uuid>d5462bb6-159e-4dbd-9266-bf8c07fa1695</uuid>
>     <memory unit='KiB'>2097152</memory>
>     <currentMemory unit='KiB'>2097152</currentMemory>
>     <vcpu placement='static'>2</vcpu>
>     <os>
>       <type arch='aarch64' machine='virt'>hvm</type>
>       <loader readonly='yes'
> type='pflash'>/usr/share/edk2.git/aarch64/QEMU_EFI-pflash.raw</loader>
>       <nvram>/var/lib/libvirt/qemu/nvram/cent7_VARS.fd</nvram>
>       <boot dev='hd'/>
>     </os>
>     <cpu mode='host-passthrough'/>
>     <clock offset='utc'/>
>     <on_poweroff>destroy</on_poweroff>
>     <on_reboot>restart</on_reboot>
>     <on_crash>restart</on_crash>
>     <devices>
>       <emulator>/usr/bin/kvm</emulator>
>       <disk type='file' device='disk'>
>         <driver name='qemu' type='qcow2'/>
>         <source file='/var/lib/libvirt/images/cent7-2.img'/>
>         <target dev='sda' bus='scsi'/>
>         <address type='drive' controller='0' bus='0' target='0' unit='0'/>
>       </disk>
>       <disk type='file' device='cdrom'>
>         <driver name='qemu' type='raw'/>
>         <target dev='sdb' bus='scsi'/>
>         <readonly/>
>         <address type='drive' controller='0' bus='0' target='0' unit='1'/>
>       </disk>
>       <disk type='file' device='disk'>
>         <driver name='qemu' type='qcow2'/>
>         <source file='/var/lib/libvirt/images/cent7-10.img'/>
>         <target dev='sdc' bus='scsi'/>
>         <address type='drive' controller='0' bus='0' target='0' unit='2'/>
>       </disk>
>       <disk type='file' device='disk'>
>         <driver name='qemu' type='qcow2'/>
>         <source file='/var/lib/libvirt/images/cent7-11.img'/>
>         <target dev='sdd' bus='scsi'/>
>         <address type='drive' controller='0' bus='0' target='0' unit='3'/>
>       </disk>
>       <disk type='file' device='disk'>
>         <driver name='qemu' type='qcow2'/>
>         <source file='/var/lib/libvirt/images/cent7-13.img'/>
>         <target dev='sdv' bus='scsi'/>
>         <address type='drive' controller='3' bus='0' target='0' unit='0'/>
>       </disk>
>       <controller type='scsi' index='0' model='virtio-scsi'>
>         <address type='virtio-mmio'/>
>       </controller>
>       <controller type='scsi' index='1'>
>         <address type='virtio-mmio'/>
>       </controller>
>       <controller type='scsi' index='2'>
>         <address type='virtio-mmio'/>
>       </controller>
>       <controller type='scsi' index='3' model='virtio-scsi'>
>         <address type='virtio-mmio'/>
>       </controller>
>       <controller type='pci' index='0' model='pcie-root'/>
>       <controller type='pci' index='1' model='dmi-to-pci-bridge'>
>         <model name='i82801b11-bridge'/>
>         <address type='pci' domain='0x0000' bus='0x00' slot='0x01'
> function='0x0'/>
>       </controller>
>       <controller type='pci' index='2' model='pci-bridge'>
>         <model name='pci-bridge'/>
>         <target chassisNr='2'/>
>         <address type='pci' domain='0x0000' bus='0x01' slot='0x01'
> function='0x0'/>
>       </controller>
>       <interface type='bridge'>
>         <mac address='52:54:00:a1:6e:75'/>
>         <source bridge='br0'/>
>         <model type='virtio'/>
>         <address type='virtio-mmio'/>
>       </interface>
>       <serial type='pty'>
>         <target port='0'/>
>       </serial>
>       <console type='pty'>
>         <target type='serial' port='0'/>
>       </console>
>     </devices>
>   </domain>
>
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>