Re: [XEN PATCH 1/7] xen: introduce XENFEAT_xenstore_late_init

[David Vrabel <dvrabel@xxxxxxxxxx>]

On 10/01/2022 22:55, Stefano Stabellini wrote:
> I have a patch for Linux that if XENFEAT_xenstore_late_init is present
> makes Linux wait for an event notification before initializing xenstore:
> https://marc.info/?l=xen-devel&m=164160299315589
>
> So with v1 of the Xen and Linux patches series:
> - Xen allocates the event channel at domain creation
> - Linux boots, sees XENFEAT_xenstore_late_init and wait for an event
> - init-dom0less later allocates the xenstore page
> - init-dom0less triggers the xenstore event channel
> - Linux receives the event and finishes the initialization, including
>    mapping the xenstore page
You can get this behaviour without the new feature.

- Xen allocates the event channel at domain creation
- Linux boots, sees HVM_PARAM_STORE_PFN is invalid and there's a 
xenstore event channel and waits for an event
- init-dom0less later allocates the xenstore page
- init-dom0less triggers the xenstore event channel
- Linux receives the event and finishes the initialization, including
   mapping the xenstore page-

David