Re: [edk2-devel] [PATCH 0/9] Allocate and unblock variable runtime cache buffer in PEI

["duntan" <dun.tan@intel.com>]

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Hi Sean,

I saw the PR contribution process proposal in community. It looks good.

I agree that the existence of the HOB can indicate if the feature is used or not on the consumer side. Will move the reference to PcdEnableVariableRuntimeCache on the HOB consumer side. But I think PcdEnableVariableRuntimeCache is still needed to decide whether we need to build HOB or not.

For other comments, I’ll modify the patch series based on your comments and the sample you mentioned. Thanks for you detailed comments.

Thanks,
Dun

From: Sean Brogan <spbrogan@outlook.com>
Sent: Tuesday, May 21, 2024 2:17 AM
To: devel@edk2.groups.io; Tan, Dun <dun.tan@intel.com>
Cc: Ni, Ray <ray.ni@intel.com>; Liming Gao <gaoliming@byosoft.com.cn>; Wu, Jiaxin <jiaxin.wu@intel.com>; Ard Biesheuvel <ardb+tianocore@kernel.org>; Leif Lindholm <quic_llindhol@quicinc.com>; Sami Mujawar <sami.mujawar@arm.com>; Gerd Hoffmann <kraxel@redhat.com>; Andrew Fish <afish@apple.com>; Yao, Jiewen <jiewen.yao@intel.com>
Subject: Re: [edk2-devel] [PATCH 0/9] Allocate and unblock variable runtime cache buffer in PEI


I can't find patch 1 in the series in my email so putting a few comments here.  I really hope this patch series can wait for PRs so code comments can more easily be correlated with code change.

Looking at your PR with commit: Allocate Varaible cache buffer in PEI by td36 · Pull Request #5607 · tianocore/edk2 (github.com)<https://github.com/tianocore/edk2/pull/5607/commits/36c2cac5fa4196be7fc85d842e8056e376010479>

A few comments for now.

Variable is spelled incorrectly in commit message.

I would really prefer to not mix PCDs and Hobs.  It is really confusing what has to be turned on and set to what to get the different behaviors.  For a hob producer it is OK to take that info from PCDs but lets not mix in the consumer code PCDs and hob data.  The HOB definition should not reference a PCD and a HOB definition should not be focused on producer/consumer but on the data.

The existence of a hob is also a good indicator that a feature is used so you may not need to have "enable" PCDs anymore.

Please don't include other header files in public header files (especially for super common headers like PiPei.h.  i know over the last few years this practice has become more common but it just creates pain when debugging build errors.  The trade off is not worth it.

Hobs really shouldn't use UINTN sizes.  Since hobs helps transfer config state across phases where the size of UINTN may be different this causes problems.

Hobs used for cross phase sharing shouldn't have pointers for the reason.

Better and more complete comments on the different field members would be helpful.  I assume the "Buffer" fields are physical addresses and the "Pages" are number of 4K pages.   I would suggest EFI_PHYSICAL_ADDRESS for addresses and UINT64 for lengths.

More details on what the three cache's are would be helpful or at least reference the feature of the cache they are supporting.

This hob definition file isn't perfect and I believe some of the comment in the file header belong in different places, it is at least a good template for a hob definition.

edk2/MdeModulePkg/Include/Guid/VariableFlashInfo.h at 284dbac43da752ee34825c8b3f6f9e8281cb5a19 · tianocore/edk2 (github.com)<https://github.com/tianocore/edk2/blob/284dbac43da752ee34825c8b3f6f9e8281cb5a19/MdeModulePkg/Include/Guid/VariableFlashInfo.h>



Thanks

Sean




On 5/17/2024 2:49 AM, duntan wrote:

This patch set defines a new VARIABLE_RUNTIME_CACHE_INFO HOB. The HOB is used to store the address and size of the buffer that will be used for variable runtime service when the PcdEnableVariableRuntimeCache is TRUE.

In following patches, when PcdEnableVariableRuntimeCache is TRUE, VariablePei will install a callback of gEfiPeiMemoryDiscoveredPpiGuid to allocate the needed buffer for different type variable runtime cache and build the HOB.

Then VariableSmmRuntimeDxe driver will consume gEdkiiVariableRuntimeCacheInfoHobGuid to initialize the variable runtime cache related content. The code to allocate and unblock the runtime cache buffer in VariableSmmRuntimeDxe is also removed in this patc set.



PR for review: https://github.com/tianocore/edk2/pull/5607



Cc: Ray Ni <ray.ni@intel.com><mailto:ray.ni@intel.com>

Cc: Liming Gao <gaoliming@byosoft.com.cn><mailto:gaoliming@byosoft.com.cn>

Cc: Jiaxin Wu <jiaxin.wu@intel.com><mailto:jiaxin.wu@intel.com>

Cc: Ard Biesheuvel <ardb+tianocore@kernel.org><mailto:ardb+tianocore@kernel.org>

Cc: Leif Lindholm <quic_llindhol@quicinc.com><mailto:quic_llindhol@quicinc.com>

Cc: Sami Mujawar <sami.mujawar@arm.com><mailto:sami.mujawar@arm.com>

Cc: Gerd Hoffmann <kraxel@redhat.com><mailto:kraxel@redhat.com>

Cc: Andrew Fish <afish@apple.com><mailto:afish@apple.com>

Cc: Jiewen Yao <jiewen.yao@intel.com><mailto:jiewen.yao@intel.com>



Dun Tan (9):

  MdeModulePkg:Add new gEdkiiVariableRuntimeCacheInfoHobGuid

  ArmVirtPkg: Add MmUnblockMemoryLib in DSC

  EmulatorPkg: Add MmUnblockMemoryLib in DSC

  OvmfPkg: Add MmUnblockMemoryLib in DSC

  MdeModulePkg:Create gEdkiiVariableRuntimeCacheInfoHobGuid

  MdeModulePkg:Remove unnecessary global variable

  MdeModulePkg:Consume gEdkiiVariableRuntimeCacheInfoHobGuid

  MdeModulePkg: Refine InitVariableCache()

  MdeModulePkg:Add global variable mVariableRtCacheInfo



 ArmVirtPkg/ArmVirtCloudHv.dsc                                        |   2 ++

 EmulatorPkg/EmulatorPkg.dsc                                          |   1 +

 MdeModulePkg/Include/Guid/VariableRuntimeCacheInfo.h                 |  65 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

 MdeModulePkg/MdeModulePkg.dec                                        |   3 +++

 MdeModulePkg/Universal/Variable/Pei/Variable.c                       | 298 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-

 MdeModulePkg/Universal/Variable/Pei/Variable.h                       |   3 +++

 MdeModulePkg/Universal/Variable/Pei/VariablePei.inf                  |   8 +++++++-

 MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmmRuntimeDxe.c   | 293 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-------------------------------------------------------------------------------------------------------------------------------------------------------------------------

 MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmmRuntimeDxe.inf |   5 +++--

 OvmfPkg/OvmfPkgIa32X64.dsc                                           |   2 +-

 10 files changed, 506 insertions(+), 174 deletions(-)

 create mode 100644 MdeModulePkg/Include/Guid/VariableRuntimeCacheInfo.h




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