[Pkg-libvirt-maintainers] Bug#1107536: Bug#1107536: PPC64LE: Device hotplug/unplug requires guest reboot

[Andrea Bolognani]

On Tue, Jun 10, 2025 at 12:29:45PM +0530, Trupti wrote:
> On 2025-06-09 23:38, Andrea Bolognani wrote:
> > What's the output of attach-interface if you pass the --print-xml
> > flag to it? What does the full live XML look like before and after
> > the operation?
> 
> I have gathered the diagnostic information you requested.
> 
>   virsh attach-interface --live vm bridge --source virbr0 --print-xml
> 
> The command produced the following output:
> 
>   <interface type='bridge'>
>      <source bridge='virbr0'/>
>   </interface>
> 
> I have attached the two files, before.xml and after.xml.

Checking the difference between the two:

  $ diff -Naru before.xml after.xml
  --- before.xml  2025-06-10 20:32:21.630608513 +0200
  +++ after.xml   2025-06-10 20:32:02.658407208 +0200
  @@ -60,6 +60,14 @@
         <alias name='net0'/>
         <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'/>
       </interface>
  +    <interface type='bridge'>
  +      <mac address='52:54:00:a2:19:7a'/>
  +      <source bridge='virbr0'/>
  +      <target dev='vnet3'/>
  +      <model type='rtl8139'/>
  +      <alias name='net1'/>
  +      <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
  +    </interface>
       <serial type='pty'>
         <source path='/dev/pts/1'/>
         <target type='spapr-vio-serial' port='0'>

That rtl8139 model doesn't seem right for a ppc64le guest. Try
passing

  --model virtio

to virsh attach-interface. That'd be a good idea in general, you
always want to use virtio if possible.

> > Honestly this sounds like a guest OS issue rather than a bug in
> > libvirt. Is any message produced in dmesg/journal as a consequence of
> > the hotplug operation?
> 
> The guest dmesg shows the RTAS hot-plug signal, but no further messages
> appear.

This seems to confirm my theory: libvirt and QEMU successfully
performed the hotplug, the OS detected that happening, then something
went wrong. Probably the ppc64le OS simply doesn't come with the
driver for the rtl8139 network device.

-- 
Andrea Bolognani <eof at kiyuko.org>
Resistance is futile, you will be garbage collected.
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