-----Original Message-----
From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Laszlo
Ersek
Sent: Friday, June 19, 2020 8:48 PM
To: rfc@edk2.groups.io; Bi, Dandan <dandan.bi@...>;
devel@edk2.groups.io
Cc: Dong, Eric <eric.dong@...>; Ni, Ray <ray.ni@...>; Wang,
Jian J <jian.j.wang@...>; Wu, Hao A <hao.a.wu@...>; Tan,
Ming <ming.tan@...>
Subject: Re: [edk2-devel] [edk2-rfc] MdeModulePkg/StatusCodeHandler:
Separate NULL class libraries for Memory and serial handlers from
MdeModulePkg/Universal/StatusCodeHandler modules

On 06/18/20 09:01, Dandan Bi wrote:

Hi All,

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2816

We plan to separate two kinds of NULL class libraries for Memory and serial

handlers from MdeModulePkg/Universal/StatusCodeHandler/.../
StatusCodeHandlerPei/RuntimeDxe/Smm modules.

The benefit we want to gain from this separation is to 1) make the code

clear and easy to maintain, 2) make platform flexible to choose any handler
library they need, and it also can reduce image size since the unused
handlers can be excluded.

If you have any concern or comments for this separation, please let me

know.

We plan to add new separated NULL class library

MemoryStausCodeHandlerLib and SerialStatusCodeHandlerLib with different
phase implementation into MdeModulePkg\Library\ directory.

The main tree structure may like below:
MdeModulePkg\Library
|------MemoryStausCodeHandlerLib
|------|------ PeiMemoryStausCodeHandlerLib.inf
|------|------ RuntimeDxeMemoryStatusCodeHandlerLib.inf
|------|------ SmmMemoryStausCodeHandlerLib.inf
|------SerialStatusCodeHandlerLib
|------|------ PeiSerialStatusCodeHandlerLib.inf
|------|------ RuntimeDxeSerialStatusCodeHandlerLib.inf
|------|------ SmmSerialStatusCodeHandlerLib.inf


We will update existing platform use cases in edk2 and edk2-platform repo

to cover the new NULL class library to make sure this change doesn't impact
any platform.

After this separation, StatusCodeHandler module usage will like below, and

it's also very flexible for platform to cover more handler libraries to meet
their requirements.

MdeModulePkg/Universal/StatusCodeHandler/Pei/StatusCodeHandlerPei.in
f {

<LibraryClasses>

NULL|MdeModulePkg/Library/MemoryStausCodeHandlerLib/PeiMemorySt
ausCode

NULL|HandlerLib.inf

NULL|MdeModulePkg/Library/SerialStatusCodeHandlerLib/PeiSerialStatusC
o

NULL|deHandlerLib.inf
...
}

MdeModulePkg/Universal/StatusCodeHandler/RuntimeDxe/StatusCodeHan
dlerRuntimeDxe.inf {

<LibraryClasses>

NULL|MdeModulePkg/Library/MemoryStausCodeHandlerLib/RuntimeDxeM
emorySt

NULL|ausCodeHandlerLib.inf

NULL|MdeModulePkg/Library/SerialStatusCodeHandlerLib/RuntimeDxeSeri
alS

NULL|tatusCodeHandlerLib.inf
...
}

MdeModulePkg/Universal/StatusCodeHandler/Smm/StatusCodeHandlerSm
m.inf {

<LibraryClasses>

NULL|MdeModulePkg/Library/MemoryStausCodeHandlerLib/SmmMemory
StausCode

HandlerLib.inf

NULL|MdeModulePkg/Library/SerialStatusCodeHandlerLib/SmmSerialStatus
Co

NULL|deHandlerLib.inf
...
}

So I assume you're going to remove PcdStatusCodeUseSerial and
PcdStatusCodeUseMemory, and when converting the existent platforms,
the new NULL class resolutions in the DSC files will reflect the specific PCD
values used in those DSC files until then. Is that right?

Thanks for pointing out the PCD part which I miss in this RFC.
This commit https://github.com/tianocore/edk2/commit/45bc28172fbf38ac21e2592c07189b55f57695e3 have updated PcdStatusCodeUseSerial and PcdStatusCodeUseMemory type.
We plan to keep PcdStatusCodeUseSerial and PcdStatusCodeUseMemory. Through NULL class resolutions in the DSC can make the code handler code included or not, then we still can control handler enable/disable through the PCD dynamically if the handler is included.
What do you think of this?