How to make it so that a "reboot" is enough to apply pending QEMU settings changes ?

[shodan]

Hi,

I rebooted this machine, but the settings did not apply.


I think during the reset itself, proxmox should reset or reload settings on the QEMU process.
The alternative is that you have to fully shutdown and go in and restart it. I would like it to be enough to reboot from the guest OS and the pending changes would apply !

 

[Impact]

You need to reboot via the GUI's reboot button. Hint: hover over it

 

[BobhWasatch]

I would like it to be enough to reboot from the guest OS and the pending changes would apply !

I think that might be impossible because hardware changes require restarting QEMU, which a guest reboot does not do. Do what @Impact says.

 

[Impact]

Somewhat related: https://bugzilla.proxmox.com/show_bug.cgi?id=7213

 

[BobhWasatch]

So there is a feature of QEMU that makes it possible with some external tooling. Nice.

 

[robertlukan]

I hope this gets merged soon, as it is super useful feature.

 

[shodan]

Ok, I test
Without guest agent, nothing but a full shutdown with the VM stopping worked
With guest agent, the VM rebooting itsef, like below, doesn't work

Rebooting the VM using the external control (which require the Guest agent), that works

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That remind me, Shutdown and reboot should not even be visible as options if the guest agent it not tested-operational (and probably not hibernate either ? does it have guest-hibernate and proxmox hibernate ? If yes then we should have separate option for hypervisor hibernate and guest hibernate as those are really distinct operations )

 

[shodan]

So the big question is

Can QEMU recognize when the VM actually resets it's processor ?
I feel like that is a really special and easy to distinguish moment for the hypervisor, and it should be possible for the hypervisor orchestrator to detect that, since it has pending changes, it should re-launch the QEMU process.

And also, QEMU should be able to just enable that on fly WITHOUT a reboot, the virtual display, memory, cpu cores, audio devices, cdroms, serial ports, parrallel ports and PCIE passthrough should all be hot plug hot swap and hot disconnect

 

[Impact]

which require the Guest agent

Without it enabled it should send a ACPI signal that should still work.