[Bug 673705] Re: running guests freeze when a guest is powered down

[Serge Hallyn]

Quoting Derek Simkowiak (ubuntu at cool-st.com):
> This bug is probably a duplicate issue as this:
> 
> https://bugs.launchpad.net/ubuntu/maverick/+source/qemu-kvm/+bug/584048
> 
> The problem is with Linux bridging.  When adding or removing a MAC
> address (like for KVM, VirtualBox, or even LXC) then if the bridge
> changes its MAC, this symptom happens.  See comment #60 at the URL
> above, and also see this:
> 
> https://www.redhat.com/archives/libvir-list/2010-July/msg00450.html
> 
> The workaround is to use a MAC address that starts with "fe" (or any
> high really high number) for your guests.  This causes the kernel to
> default to the hardware MAC for the bridge.

Derek, thanks so much for this.  You're almost 100% correct.  I had even
suspected that bug (in comment #7), but I failed to make the simple
connection explaining this behavior.

The proposed solution does *not* suffice, and in fact I just reproduced
the bug in natty!

The current solution counts on the bridge being associated with a physical
NIC.  But our default configuration uses a NAT bridge which starts with
no physical devices attached.  So it starts with a zero-ed out mac addr.
Then every time you start a VM with a lower MAC address than the first
VM's, you can see this pause.  And if you shut down the VM with the
lowest MACADDR, you'll again see the pause.


** Changed in: qemu-kvm (Ubuntu)
       Status: Incomplete => Confirmed

** Changed in: linux (Ubuntu)
       Status: Incomplete => Invalid

** Changed in: qemu-kvm (Ubuntu)
   Importance: Low => High

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https://bugs.launchpad.net/bugs/673705

Title:
  running guests freeze when a guest is powered down