Re: [PATCH v3 edk2-platforms 03/23] Platform/Raspberry/Pi3: Add ACPI tables

[Pete Batard <pete@akeo.ie>]

Hi Ard, thanks for the reviews,

On 2019.01.28 13:24, Ard Biesheuvel wrote:
> A couple of general remarks on these tables.
> 
> - AFAICT (but is is difficult to tell from the binary dumps), these
> are based on ACPI 5.0, which predates the introduction of ARM support
> into the spec. That essentially makes them Windows-only, and not spec
> based, which is unfortunate. However, since this SoC does not have an
> interrupt controller permitted by ACPI, that actually does not matter
> a lot in practice.

Publicly, these tables are only meant to boot Windows and we got them 
from Microsoft. So they are not exactly meant to be ACPI compliant (for 
instance, AFAIK, there's no definition of ACPI that includes the RPI 
interrupt controller).

As such, we really don't want to touch these because we have run into 
nightmarish situation where Windows wouldn't boot at all after we tried 
to alter them.

In other words, if we are to try to change much in here, we will 
probably need to have Microsoft's involvement...

> - _CID fields should be properly formatted ACPI or PNP handles, you
> can't put arbitrary strings in there (like BCMAUXSPI or VC4)

The Microsoft Windows drivers expect those exact IDs, so that's not 
something we can alter either. Once again, these ACPI tables were not 
designed to be ACPI compliant, and making them so that late in the game 
is going to break a lot of things downstream, so we don't believe that 
we can do that at this stage.


I will apply your other request for ACPI (drop the "-mcmodel=tiny" 
workaround in [BuildOptions]), as well as the changes you requested for 
1/2/19 and, if you are okay with having our hands tied with regards to 
ACPI compliance, submit a v4 later on today.

Regards,

/Pete