Re: [Xen-devel] [PATCH v2] clarify SHUTDOWN_suspend additional argument

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 08/05/14 16:43, Stefano Stabellini wrote:
> Clarify the behaviour of SCHEDOP_shutdown: PV x86 guests need to pass a
> third argument, that is unused on HVM and ARM guests.
>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
>
> diff --git a/xen/include/public/sched.h b/xen/include/public/sched.h
> index a30b11d..4000ac9 100644
> --- a/xen/include/public/sched.h
> +++ b/xen/include/public/sched.h
> @@ -76,9 +76,10 @@
>   * Halt execution of this domain (all VCPUs) and notify the system 
> controller.
>   * @arg == pointer to sched_shutdown_t structure.
>   *
> - * If the sched_shutdown_t reason is SHUTDOWN_suspend then this
> - * hypercall takes an additional extra argument which should be the
> - * MFN of the guest's start_info_t.
> + * If the sched_shutdown_t reason is SHUTDOWN_suspend then
> + * x86 PV guests must also set RDX (EDX for 32-bit guests) to the MFN
> + * of the guest's start info page.  RDX/EDX is the third hypercall
> + * argument.

Its still a little awkward to read.  How about

@arg2 == mfn of start_info_t (x86 PV only)

above this paragraph.

Explaining which parameters live in which registers is tangential to the
point of "this is a 3 argument hypercall for x86 pv and 2 argument for
all other types of domains"

~Andrew

>   *
>   * In addition, which reason is SHUTDOWN_suspend this hypercall
>   * returns 1 if suspend was cancelled or the domain was merely
>
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