Re: [Xen-devel] Trigger code in domU from dom0

[Christopher Head <chead@xxxxxxxxx>]

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Hi,
I'm doing something very similar for a research project. Assuming your
domU is PV, look in linux/drivers/xen/core/reboot.c and
linux/drivers/xen/core/machine_reboot.c. You'll discover that the dom0
tools don't actually suspend the domU for migration: instead, they send
an event channel event to domU which then suspends itself via a
hypercall. All you have to do is pick a place sufficiently close to the
hypercall to run your own code.

Note that this is SMP safe as well: one of the first things the kernel
does when the suspend message is received is shut down all CPUs except
for #0, so only #0 will be alive around the hypercall. Combining that
with the lack of preemption in the Xen kernel, you have a situation
where your code is guaranteed to run before anything else.

Chris

Asim wrote:
| Hi,
|
| I want to trigger some code in my domU as soon as migration happens. I
| can only know when to trigger in my destination dom0 but the code
| should trigger in domU.
| How do I go about doing this? Is there any script that completes or is
| running that executes when a migration finishes or is about to finish?
|
| Regards,
| Asim
|
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