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SubjectRe: [PATCH v3] dcdbas: Add support for WSMT ACPI table
On Mon, Jul 2, 2018 at 5:07 PM,  <> wrote:

>> >> OK, now the most important question, did you investigate "SMM
>> >> Communication ACPI Table"?
>> >> Can you utilize information in it?
>> > Dell BIOS does not provide a "SMM Communication ACPI Table", just the EPS. It
>> appears
>> > that the "SMM Communication ACPI Table" is deprecated in the UEFI 2.7 spec.
>> Also, the
>> > dcdbas driver is for Dell systems only.
>> > The EPS table isn't an ACPI table,
>> > it's just a Dell-defined table.
>> Hmm... It's either strange or has some background why is so.
>> OK it has a note that there is no use case, but here it is!
>> Mario, can we consider this as a BIOS bug which doesn't provide SMM
>> Communication ACPI table?
>> Can it be escalated on UEFI committee?

> I don't believe SMM communication ACPI table has ever been implemented by Dell
> on server or client BIOS. I do agree this table describes the behavior that DCDBAS driver
> has used since before even UEFI BIOS pretty accurately.

So, EPS table has been for ages in Dell machines?
Can we consider it as a predecessor of that SMM communication ACPI table?

> Stuart and I did discuss with server BIOS (who uses this EPS mechanism) to see if its possible
> to move EPS to SMM communication ACPI table however since it's been deprecated by
> UEFI 2.7 they weren't willing to adopt it.

It's pity, but the motivation to deprecate is "lack of use" which is
not true. That's why I would suggest to escalate this to UEFI

> Stuart, anything else you want to add here?

Darren, what's your opinion about this?

P.S. I'm not against this approach (just some technical comments I
already shared), but on the other hand it would be nice to have undo
that deprecation and follow the standard in new firmwares.
Would you agree?

With Best Regards,
Andy Shevchenko

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