Re: [Xen-devel] [PATCH 08/17 v5] xen/arm: vpl011: Add a new domctl API to initialize vpl011

[Julien Grall <julien.grall@xxxxxxx>]

On 23/06/17 00:04, Stefano Stabellini wrote:
> > diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
> > index 1629f41..26f3d1e 100644
> > --- a/tools/libxc/include/xenctrl.h
> > +++ b/tools/libxc/include/xenctrl.h
> > @@ -885,6 +885,26 @@ int xc_vcpu_getcontext(xc_interface *xch,
> >                         uint32_t vcpu,
> >                         vcpu_guest_context_any_t *ctxt);
> >
> > +#if defined (__arm__) || defined(__aarch64__)
> > +/**
> > + * This function initializes the vpl011 emulation and returns
> > + * the event to be used by the backend for communicating with
> > + * the emulation code.
> > + *
> > + * @parm xch a handle to an open hypervisor interface
> > + * @parm domid the domain to get information from
> > + * @parm console_domid the domid of the backend console
> > + * @parm gfn the guest pfn to be used as the ring buffer
> > + * @parm evtchn the event channel to be used for events
> > + * @return 0 on success, negative error on failure
> > + */
> > +int xc_dom_vpl011_init(xc_interface *xch,
> > +                       uint32_t domid,
> > +                       uint32_t console_domid,
> > +                       xen_pfn_t gfn,
> > +                       evtchn_port_t *evtchn);
> > +#endif
> Actually, the pattern is to define the xc_ function on all architecture
> but only return ENOSYS where it's not implemented, see
> xc_vcpu_get_extstate.
Well, I think the main reason behind if to avoid dummy call to the 
hypervisor. But effectively the hypervisor will return a proper error.
As the call is not made in common code, I would make this function 
compile on all the platform (there are nothing arch specific in it).
Cheers,

--
Julien Grall

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