Re: [PATCH 3/3] Documentation/arm64: Update ACPI tables from BBR

[Hanjun Guo <guohanjun@huawei.com>]

On 2023/5/18 21:40, Robin Murphy wrote:
> On 2023-05-18 13:07, Hanjun Guo wrote:
>> Hi Jose,
>>
>> On 2023/5/18 18:52, Jose Marinho wrote:
>>> The BBR specification requires (or conditionally requires) a set of ACPI
>>> tables for a proper working system.
>>> This commit updates:
>>> - the list of ACPI tables to reflect the contents of
>>> BBR version 2.0 (see https://developer.arm.com/documentation/den0044/g).
>>> - the list of ACPI tables in acpi_object_usage. This last update ensures
>>> that both files remain coherent.
>>
>> Thanks for the update, some comments inline.
>>
>>>
>>> Signed-off-by: Jose Marinho <jose.marinho@arm.com>
>>> Reviewed-by: Samer El-Haj-Mahmoud <Samer.El-Haj-Mahmoud@arm.com>
>>> ---
>>>   Documentation/arm64/acpi_object_usage.rst | 81 +++++++++++++++++++++--
>>>   Documentation/arm64/arm-acpi.rst          | 71 +++++++++++++++++---
>>>   2 files changed, 139 insertions(+), 13 deletions(-)
>>>
>>> diff --git a/Documentation/arm64/acpi_object_usage.rst 
>>> b/Documentation/arm64/acpi_object_usage.rst
>>> index 484ef9676653..1da22200fdf8 100644
>>> --- a/Documentation/arm64/acpi_object_usage.rst
>>> +++ b/Documentation/arm64/acpi_object_usage.rst
>>> @@ -17,16 +17,37 @@ For ACPI on arm64, tables also fall into the 
>>> following categories:
>>>          -  Recommended: BERT, EINJ, ERST, HEST, PCCT, SSDT
>>> -       -  Optional: BGRT, CPEP, CSRT, DBG2, DRTM, ECDT, FACS, FPDT, 
>>> IBFT,
>>> -          IORT, MCHI, MPST, MSCT, NFIT, PMTT, RASF, SBST, SLIT, 
>>> SPMI, SRAT,
>>> -          STAO, TCPA, TPM2, UEFI, XENV
>>> +       -  Optional: AGDI, BGRT, CEDT, CPEP, CSRT, DBG2, DRTM, ECDT, 
>>> FACS, FPDT,
>>> +          HMAT, IBFT, IORT, MCHI, MPAM, MPST, MSCT, NFIT, PMTT, 
>>> PPTT, RASF, SBST,
>>> +          SDEI, SLIT, SPMI, SRAT, STAO, TCPA, TPM2, UEFI, XENV
>>> -       -  Not supported: BOOT, DBGP, DMAR, ETDT, HPET, IVRS, LPIT, 
>>> MSDM, OEMx,
>>> -          PSDT, RSDT, SLIC, WAET, WDAT, WDRT, WPBT
>>> +       -  Not supported: AEST, APMT, BOOT, DBGP, DMAR, ETDT, HPET, 
>>> IVRS, LPIT,
>>
>> AEST is ARM Error Source Table, and it can be used for ARM platforms, so
>> I thinsk AEST is not belong to "Not supportted", "Optional" instead.
> 
> Can you point to the code in Linux which does anything with AEST, 
> optionally or otherwise? ;)
>> and APMT is the same.
>>
>>> +          MSDM, OEMx, PDTT, PSDT, RAS2, RSDT, SLIC, WAET, WDAT, 
>>> WDRT, WPBT
>>
>> PDTT and RAS2 are now used for ARM too, please move it to Optional :)
> 
> Ditto; as stated in arm-acpi.rst this is Linux documentation covering 
> the interaction between Linux and ACPI. It is not some kind of generic 

Hmm, let me see...

OK, I checked the arm-acpi.rst, it is saying:

"Detailed expectations for ACPI tables and object are listed in the file
Documentation/arm64/acpi_object_usage.rst."

So if I remember correctly, it is the guidance of ACPI tables and
methods usage on arm64, to align with the BBR.

> ACPI-on-Arm guidance whitepaper. If and when Linux actually supports 
> these tables in the sense of meaningfully consuming them, that is when 
> we can document such support.

If this is the case, we don't need categories of "Required",
"Recommmened" and etc.

Thanks
Hanjun