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

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2014-05-08 at 18:27 +0100, Stefano Stabellini wrote:
> On Thu, 8 May 2014, Andrew Cooper wrote:
> > 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"
> 
> The current version is easier to understand for me.

It's as good a starting point as any, so I have acked + applied. If
anyone wants to clarify further they are welcome to do so.

Ian.


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