Re: [PATCH] libxc: Document xc_domain_resume

[Dario Faggioli <dario.faggioli@citrix.com>]

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On Wed, 2016-03-30 at 11:10 -0400, Konrad Rzeszutek Wilk wrote:
> 
> --- a/tools/libxc/include/xenctrl.h
> +++ b/tools/libxc/include/xenctrl.h
> @@ -565,6 +565,58 @@ int xc_domain_destroy(xc_interface *xch,
> 
> + * HVM guest are the simplest - they suspend via S3 and resume from
> + * S3. Upon resume they have to re-negotiate with the emulated
> devices.
> + *
> + * PV and PVHVM communicate via via hypercalls for suspend (and 
                               ^repeated "via"

> resume).
> + * For suspend the toolstack initiaties the process by writting an
> value in
> + * XenBus "control/shutdown" with the string "suspend".
> + *
> + * The PV guest stashes anything it deems neccessary in 'struct
> start_info'
> + * in case of failure (PVHVM may ignore this) and calls the
> + * SCHEDOP_shutdown::SHUTDOWN_suspend  hypercall (for PV as argument
> it
> + * passes the MFN to 'struct start_info').
> + *
> + * And then the guest is suspended.
> + *
> + * At this point the guest may be resumed on the same host under the
> same
> + * domain (checkpointing or suspending failed), or on a different
> host.
>
I think there's also the case of "same host, different domain", as it
happens in local migrations, but maybe it's not that important to
mention it here.

> + * If the resume was not checkpointing (or if suspend was succesful)
> we would
> + * setup the PV timers and the different PV events. Lastly the PV
> drivers
> + * re-negotiate with the backend.
                            ^backends ?

Regards,
Dario
-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)


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