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

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

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@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Michael Kubacki
> Sent: Friday, August 20, 2021 12:53 AM
> To: devel@edk2.groups.io; Ni, Ray <ray.ni@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@linux.microsoft.com>
> > *Sent:* Friday, August 13, 2021 10:16 AM
> > *To:* Ni; Ni, Ray <ray.ni@intel.com>; devel@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.
> >
> >
> 
> 
> 
>