Re: [PATCH 5/6] MdeModulePkg/VariableRuntimeDxe: factor out boot service accesses

["Zeng, Star" <star.zeng@intel.com>]

On 2019/1/10 10:33, Wang, Jian J wrote:
> Laszlo,
> 
> Regards,
> Jian
> 
>> -----Original Message-----
>> From: Laszlo Ersek [mailto:lersek@redhat.com]
>> Sent: Tuesday, January 08, 2019 11:38 PM
>> To: Ard Biesheuvel <ard.biesheuvel@linaro.org>; edk2-devel@lists.01.org
>> Cc: Leif Lindholm <leif.lindholm@linaro.org>; Kinney, Michael D
>> <michael.d.kinney@intel.com>; Gao, Liming <liming.gao@intel.com>; Wang,
>> Jian J <jian.j.wang@intel.com>; Wu, Hao A <hao.a.wu@intel.com>; Jagadeesh
>> Ujja <jagadeesh.ujja@arm.com>; Achin Gupta <Achin.Gupta@arm.com>;
>> Thomas Panakamattam Abraham <thomas.abraham@arm.com>; Sami Mujawar
>> <Sami.Mujawar@arm.com>
>> Subject: Re: [PATCH 5/6] MdeModulePkg/VariableRuntimeDxe: factor out boot
>> service accesses
>>
>> On 01/03/19 19:28, Ard Biesheuvel wrote:
>>> In preparation of providing a standalone MM based variable runtime
>>> driver, move the existing SMM driver to the new MM services table,
>>> and factor out some pieces that are specific to the traditional
>>> driver, mainly related to the use of UEFI boot services, which are
>>> not accessible to standalone MM drivers.
>>>
>>> Contributed-under: TianoCore Contribution Agreement 1.1
>>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>>> ---
>>>   MdeModulePkg/Universal/Variable/RuntimeDxe/TcgMorLockSmm.c         |  18
>> +---
>>>   MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.h              |  50
>> +++++++++
>>>   MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmm.c           |  59
>> ++++------
>>>   MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmm.inf         |   5 +-
>>>   MdeModulePkg/Universal/Variable/RuntimeDxe/VariableTraditionalMm.c |
>> 114 ++++++++++++++++++++
>>>   5 files changed, 187 insertions(+), 59 deletions(-)
>>
>> I *vaguely* feel like we should extract the new functions to
>> "PrivilegePolymorphic.h", rather than to "Variable.h".
>>
>> Please see initial commit 00663d047fc9
>> ("MdeModulePkg/Variable/RuntimeDxe: move SecureBootHook() decl to new
>> header", 2017-10-10), and other commits that touched that file.
>>
>> I realize this is not a 100% "constructive" suggestion, and I feel
>> appropriately bad about that. It's just that "Variable.h" has so many
>> internals that I feel it's not a good dumping ground for these new
>> functions. And the other header we have, looks closer in purpose.
>>
>> For example, MorLockInitAtEndOfDxe() is already declared in
>> "PrivilegePolymorphic.h" (see commit f1304280435f,
>> "MdeModulePkg/Variable/RuntimeDxe: introduce MorLockInitAtEndOfDxe()
>> hook", 2017-10-10).
>>
>> Admittedly, now that we're going to have three separate builds of this
>> driver, dedicating a separate header file to each "shared between A and
>> B" relationship is getting a bit too complex. In retrospect, introducing
>> "PrivilegePolymorphic.h" may not have been a "scalable" idea, after all,
>> and I should have just dumped those functions all in "Variable.h".
>>
>> IOW, I think
>> - targeting "Variable.h" now is inconsistent with earlier code,
>> - extending "PrivilegePolymorphic.h" is also suboptimal (although still
>> better than the previous option),
>> - adding yet another header might be technically correct, but it would
>> be over-engineering,
>> - asking you to merge "PrivilegePolymorphic.h" back into "Variable.h"
>> feels awkward, especially after I argued *for* "PrivilegePolymorphic.h"
>> at length, when I originally introduced it. :/
>>
>> Sigh. Can the variable driver maintainers comment please?
>>
>> (I still plan to regression-test this series, but I feel like I should
>> force myself to at least skim the variable driver patches, beyond
>> testing them. Because, next time I can't avoid working with this very
>> complex driver, I wouldn't like to be *completely* lost.)
>>
> 
> I agree "PrivilegePolymorphic.h" is more appropriate place for them.
> Maybe Star have different opinion.

At current situation, I prefer PrivilegePolymorphic.h. :)

Some minor feedback will be added in another reply.

Thanks,
Star

> 
>> Thanks,
>> Laszlo