Re: Does ARM platform produce MP protocol?

["Ni, Ray" <ray.ni@intel.com>]

> -----Original Message-----
> From: edk2-devel <edk2-devel-bounces@lists.01.org> On Behalf Of Ard
> Biesheuvel
> Sent: Wednesday, March 6, 2019 3:38 PM
> To: Ni, Ray <ray.ni@intel.com>
> Cc: edk2-devel@lists.01.org
> Subject: Re: [edk2] Does ARM platform produce MP protocol?
> 
> On Wed, 6 Mar 2019 at 06:44, Ni, Ray <ray.ni@intel.com> wrote:
> >
> > Ard, Leif,
> > I am a bit interested in how ARM platform supports the MP?
> > PI Spec defines below protocol but I failed to find a driver in ARM platform
> producing this protocol.
> > Or did I miss anything?
> >
> 
> No you are right. We don't expose that on ARM, since UEFI only runs on a
> single core. Bringing up and taking down cores is done via a protocol called
> PSCI, which is implemented by firmware running at a higher privilege level.
> 
> So while it would be possible to implement the MP protocol on top of PSCI,
> we haven't identified a use case for it yet. (The OS calls PSCI directly to boot
> the secondary cores)

Is below EFI_MM_MP_PROTOCOL (added in PI spec 1.6) implemented in ARM?
Or will it be implemented by an ARM module?
I am asking this because MP_SERVICES protocol exposes CPU location information
(Package/Core/Thread) through *GetProcessorInfo*, but MM_MP protocol doesn't
have a way to expose that information.
If such location information isn't exposed by MM_MP, is that because ARM doesn't
care about the location information? Or because ARM cares but forgot to add similar
*GetProcessorInfo* interface to MM_MP when changing the PI spec?
Or ARM doesn't use the MM_MP at all?

typedef struct _EFI_MM_MP_PROTOCOL {
	UINT32                           Revision,
	UINT32                           Attributes,
	EFI_MM_ GET_NUMBER_OF_PROCESSORS GetNumberOfProcessors,
	EFI_MM_DISPATCH_PROCEDURE        DispatchProcedure,
	EFI_MM_BROADCAST_PROCEDURE       BroadcastProcedure,
	EFI_MM_SET_STARTUP_PROCEDURE     SetStartupProcedure,
	EFI_CHECK_FOR_PROCEDURE          CheckOnProcedure,
	EFI_WAIT_FOR_PROCEDURE           WaitForProcedure,
}EFI_MM_MP_PROTOCOL;
> 
> > typedef struct _EFI_MP_SERVICES_PROTOCOL {
> > EFI_MP_SERVICES_GET_NUMBER_OF_PROCESSORS
> GetNumberOfProcessors;
> > EFI_MP_SERVICES_GET_PROCESSOR_INFO GetProcessorInfo;
> > EFI_MP_SERVICES_STARTUP_ALL_APS StartupAllAPs;
> > EFI_MP_SERVICES_STARTUP_THIS_AP StartupThisAP;
> > EFI_MP_SERVICES_SWITCH_BSP SwitchBSP;
> EFI_MP_SERVICES_ENABLEDISABLEAP
> > EnableDisableAP; EFI_MP_SERVICES_WHOAMI WhoAmI; }
> > EFI_MP_SERVICES_PROTOCOL;
> >
> > Thanks,
> > Ray
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