Re: [openxt-dev] Re: Follow up on libxl-fix-reboot.patch

[Jason Andryuk <jandryuk@xxxxxxxxx>]

On Tue, Dec 15, 2020 at 5:22 PM Chris Rogers <crogers122@xxxxxxxxx> wrote:
>
> Hopefully I can provide a little more context.  Here is a link to the patch:
>
> https://github.com/OpenXT/xenclient-oe/blob/master/recipes-extended/xen/files/libxl-fix-reboot.patch
>
> The patch is a bit mis-named.  It does not implement 
> XEN_DOMCTL_SENDTRIGGER_RESET.  It's just a workaround to handle the missing 
> RESET implementation.
>
> Its purpose is to make an HVM guest "reboot" regardless of whether PV tools 
> have been installed and the xenstore interface is listening or not.  From the 
> client perspective that OpenXT is concerned with, this is for ease-of-use for 
> working with HVM guests before PV tools are installed.  To summarize the flow 
> of the patch:
>
> - User input causes high level toolstack, xenmgr, to do xl reboot <domid>
> - libxl hits "PV interface not available", so it tries the fallback ACPI 
> reset trigger (but that's not implemented in domctl)
> - therefore, the patch changes the RESET trigger to POWER trigger, and sets a 
> 'reboot' flag
> - when the xl create process handles the domain_death event for 
> LIBXL_SHUTDOWN_REASON_POWEROFF, we check for our 'reboot' flag.
> - It's set, so we set "action" as if we came from a real restart, which makes 
> the xl create process take the 'goto start' codepath to rebuild the domain.
>
> I think we'd like to get rid of this patch, but at the moment I don't have 
> any code or a design to propose that would implement the 
> XEN_DOMCTL_SENDTRIGGER_RESET.

I'm not sure it's possible to implement one.  Does an ACPI
reset/reboot button exist?  And then you'd have the problem that the
guest needs to be configured to react to the button.

Regards,
Jason