On 11/17/23 10:59, Chao Li wrote:
> Since some ARCH or platform not require execute code on memory during
> PEI phase, some values may transferred via CPU registers.
> 
> Adding PeiServcieTablePointerLibReg to allow set and get the PEI service
> table pointer depend by a CPU register, this library can accommodate lot
> of platforms who not require execte code on memory during PEI phase.
> 
> Adding PeiServiceTablePointerLibReg to allows setting and getting the
> PEI service table pointer via CPU registers, and the library can
> accommodate many platforms that do not need to execute code on memory
> during the PEI phase.
> 
> The idea of this library is derived from
> ArmPkg/Library/PeiServicesTablePointerLib/
> 
> BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=4584
> 
> Cc: Michael D Kinney <michael.d.kin...@intel.com>
> Cc: Liming Gao <gaolim...@byosoft.com.cn>
> Cc: Zhiguang Liu <zhiguang....@intel.com>
> Cc: Leif Lindholm <quic_llind...@quicinc.com>
> Cc: Ard Biesheuvel <ardb+tianoc...@kernel.org>
> Cc: Sami Mujawar <sami.muja...@arm.com>
> Cc: Laszlo Ersek <ler...@redhat.com>
> Cc: Sunil V L <suni...@ventanamicro.com>
> Signed-off-by: Chao Li <lic...@loongson.cn>
> ---
>  .../Library/PeiServicesTablePointerLib.h      | 37 +++++++-
>  .../PeiServicesTablePointer.c                 | 86 +++++++++++++++++++
>  .../PeiServicesTablePointerLib.uni            | 20 +++++
>  .../PeiServicesTablePointerLibReg.inf         | 40 +++++++++
>  MdePkg/MdePkg.dsc                             |  1 +
>  5 files changed, 180 insertions(+), 4 deletions(-)
>  create mode 100644 
> MdePkg/Library/PeiServicesTablePointerLibReg/PeiServicesTablePointer.c
>  create mode 100644 
> MdePkg/Library/PeiServicesTablePointerLibReg/PeiServicesTablePointerLib.uni
>  create mode 100644 
> MdePkg/Library/PeiServicesTablePointerLibReg/PeiServicesTablePointerLibReg.inf

In my opinion, the PeiServicesTablePointerLib class header should not be
extended with new interfaces. I understand that the generality is
attractive, but it is not put to use; only the loongarch architecture
applies the new interfaces (in the subsequent patch), and for example
the ARM code (ArmPkg/Library/PeiServicesTablePointerLib) is not reworked
in terms of these new interfaces.

What's more, the new library interfaces, even though they are exposed in
the lib class header, are not implemented for other architectures, so
they aren't even callable on those arches.

I'm commenting on this patch and the subsequent patch in the series
together, as seen squashed together. NB I'm not an MdePkg maintainer, so
this is just my opinion.

(1) As noted above, the library class should not be modified.

(2) Modifying the *comments* in
"MdePkg/Include/Library/PeiServicesTablePointerLib.h" is welcome, I
think, but then we might want to add a (separate!) patch for removing
the Itanium language, as edk2 no longer supports Itanium.

(3) The PeiServicesTablePointerLibReg instance should be called
PeiServicesTablePointerLibCsrKs0 or just PeiServicesTablePointerLibKs0.

This follows the example of the lib instance name
"PeiServicesTablePointerLibIdt". The whole library instance should be
loongaarch-specific IMO; there isn't much code that's being duplicated,
so the extra interfaces (internal or external) do not help with code
unification.

(4) "PeiServicesTablePointerLib.uni" should be named similarly (suffix
missing).

(5) BASE_NAME in the library instance INF file should be defined
similarly (suffix missing).

(6) The contents of the UNI file should be loongarch-specific, i.e. be
explicit about CSR KS0, in both comments and string constants.

(7) The comments in the library instance INF file should be similarly
loongarch-specific.

(8) I suggest dropping VALID_ARCHITECTURES altogether. If we want to
keep it, it should exclusively say LOONGARCH64.

(9) The new library instance should be listed in
[Components.LOONGARCH64] in MdePkg.dec.

This section does not exist yet; I suggest introducing it under
[Components.RISCV64].

(10) There need not / should not be two separate C source files; just
access the KS0 CSR in SetPeiServicesTablePointer() and
GetPeiServicesTablePointer() directly.

(11) The new library instance should probably not introduce new
references to Itanium.

Thanks,
Laszlo



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