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

["Sean" <spbrogan@outlook.com>]

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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>
> Cc: Liming Gao<gaoliming@byosoft.com.cn>
> Cc: Jiaxin Wu<jiaxin.wu@intel.com>
> Cc: Ard Biesheuvel<ardb+tianocore@kernel.org>
> Cc: Leif Lindholm<quic_llindhol@quicinc.com>
> Cc: Sami Mujawar<sami.mujawar@arm.com>
> Cc: Gerd Hoffmann<kraxel@redhat.com>
> Cc: Andrew Fish<afish@apple.com>
> Cc: Jiewen Yao<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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