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

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Tue, 11 Jan 2022, David Vrabel wrote:
> 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-

Hey David!

Yes, this is similar to what I had in mind and I managed to make it work
successfully.