[edk2-devel] [edk2-platforms][PATCH v1 1/1] IntelSiliconPkg: Add BaseSmmAccessLibNull

[Ni, Ray]

No, I don't.
I still don't think having a NULL SmmAccessLib is a good idea.

> -----Original Message-----
> From: Michael Kubacki <mikuback at linux.microsoft.com>
> Sent: Thursday, September 9, 2021 10:12 PM
> To: Ni, Ray <ray.ni at intel.com>; devel at edk2.groups.io
> Subject: Re: [edk2-devel] [edk2-platforms][PATCH v1 1/1] IntelSiliconPkg: Add BaseSmmAccessLibNull
> 
> Ray,
> 
> Do you have plans to do something here? Whether take this patch or
> refactor SmmAccessLib to a PEIM?
> 
> Thanks,
> Michael
> 
> On 8/20/2021 3:34 PM, Michael Kubacki wrote:
> > Since you asked for an example that was just one that I provided. I
> > don't think it detracts from the fact that a NULL instance makes sense
> > if the SmmAccessLib library class exists. The fact that a NULL instance
> > could not be allowed to exist is also confusing.
> >
> > I don't want to get too distracted with the example given, but I
> > completely agree that a different library instance should be used for
> > pre-memory and post-memory. I think the library interface is too broad
> > in scope and that contributes to causing this issue so I filed this BZ
> > to request the BoardInitLib API be refactored:
> > https://bugzilla.tianocore.org/show_bug.cgi?id=3578
> >
> >  From the other email thread about SmmAccessLib, I think we are on the
> > same page that the library would be better as a PEIM. Is that something
> > that could be done soon? Or could we have this until that is done?
> >
> > Thanks,
> > Michael
> >
> > On 8/20/2021 1:33 AM, Ni, Ray wrote:
> >> Null SmmAccessLib is confusing to me. Have you evaluated the option:
> >> Create two instances of BoardInitLib for pre-mem and post-mem. Pre-mem
> >> one doesn’t link to SmmAccessLib
> >>
> >>> -----Original Message-----
> >>> From: devel at edk2.groups.io <devel at edk2.groups.io> On Behalf Of
> >>> Michael Kubacki
> >>> Sent: Friday, August 20, 2021 12:53 AM
> >>> To: devel at edk2.groups.io; Ni, Ray <ray.ni at intel.com>
> >>> Subject: Re: [edk2-devel] [edk2-platforms][PATCH v1 1/1]
> >>> IntelSiliconPkg: Add BaseSmmAccessLibNull
> >>>
> >>> I don't understand your argument.
> >>>
> >>> The library class (SmmAccessLib) that already exists is the abstraction
> >>> layer. This is not introducing a new layer of abstraction. It is using
> >>> the current layer of abstraction.
> >>>
> >>> Thanks,
> >>> Michael
> >>>
> >>> On 8/19/2021 5:49 AM, Ni, Ray wrote:
> >>>> Michael,
> >>>>
> >>>> I don’t think scenario #1 is a good reason for NULL instance of
> >>>> SmmAccessLib. The root cause is BoardInitLib lib class supports pre-mem
> >>>> and post-mem board init.
> >>>>
> >>>> Below solution can avoid NULL SmmAccessLib:
> >>>>
> >>>> Create two instances of BoardInitLib for pre-mem and post-mem. Pre-mem
> >>>> one doesn’t link to SmmAccessLib.
> >>>>
> >>>> For scenario #2, if a particular platform doesn’t support S3, why does
> >>>> this platform include the PEIM?
> >>>>
> >>>> Please understand that I want to avoid introducing more abstraction
> >>>> layers.
> >>>>
> >>>> Thanks,
> >>>>
> >>>> Ray
> >>>>
> >>>> *From:* Michael Kubacki <mikuback at linux.microsoft.com>
> >>>> *Sent:* Friday, August 13, 2021 10:16 AM
> >>>> *To:* Ni; Ni, Ray <ray.ni at intel.com>; devel at edk2.groups.io
> >>>> *Subject:* Re: [edk2-devel] [edk2-platforms][PATCH v1 1/1]
> >>>> IntelSiliconPkg: Add BaseSmmAccessLibNull
> >>>>
> >>>> Sure.
> >>>>
> >>>> Scenario #1:
> >>>>
> >>>> MinPlatformPkg/PlatformInit/PlatformInitPei/PlatformInitPreMem.inf and
> >>>> MinPlatormPkg/PlatformInit/PlatformInitPei/PlatformInitPostMem.inf both
> >>>> link against an instance of BoardInitLib.
> >>>>
> >>>> Many boards link against a single BoardInitLib instance. See example -
> >>>> https://github.com/tianocore/edk2-
> >>>
> platforms/blob/cd4e6b716c7d1bcde94035e7dce14b53a553e103/Platform/Intel/KabylakeOpenBoardPkg/KabylakeRvp3/OpenB
> >>>
> >>> oardPkg.dsc#L203
> >>>> <https://github.com/tianocore/edk2-
> >>>
> platforms/blob/cd4e6b716c7d1bcde94035e7dce14b53a553e103/Platform/Intel/KabylakeOpenBoardPkg/KabylakeRvp3/OpenB
> >>>
> >>> oardPkg.dsc#L203>
> >>>>
> >>>> That BoardInitLib instance may link against SmmAccessLib.
> >>>> PlatformInitPreMem may wish to library class override the SmmAccessLib
> >>>> to the NULL instance while keeping it to non-NULL instance in
> >>>> PlatformInitPostMem.
> >>>>
> >>>> Scenario #2:
> >>>>
> >>>> A PEIM is built that checks whether the boot mode is S3. If so, it
> >>>> calls
> >>>> PeiInstallSmmAccessPpi(). A particular platform does not support S3,
> >>>> therefore, it links BaseSmmAccessLibNull as its library instance for
> >>>> SmmAccessLib.
> >>>>
> >>>>
> >>>
> >>>
> >>> 
> >>>
> >>


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