Hi all,
Would it be acceptable/feasible for AcpiTableDxe or AcpiPlatformDxe (in
MdeModulePkg) to use `EfiGetSystemConfigurationTable` to get the RSDP
and then install the tables? It's a solution that uses the regular
UefiLib, so it avoids platform-specific quirks (and as I see it, if RSDP
is in the configuration table, we probably always want those tables).
I'm sorry, I don't understand how this would help.

As I understand it, the issue is that this patchset changes MdeModulePkg to do platform-specific parsing.

Perhaps it would be an acceptable solution for platforms to retrieve the tables, then add
RSDP/them to the configuration table to be installed by AcpiTableDxe/AcpiPlatformDxe.
This allows MdeModulePkg to abstract away the parsing, only installing tables
available to it.
(Currently, UefiPayloadPkg's BlSupportDxe retrieves the data from a HOB and calls
`gBS->InstallConfigurationTable` with the address of RSDP).

I understand that this may not work for OVMF if tables are located differently in memory.

Regarding UefiPayloadPkg: AcpiTableDxe is currently compiled (listed in
DSC) but not added to a FV (not listed in FDF). So, how has this been
tested?
I assume through an out-of-tree platform. Many such core modules exist
in edk2 that are not consumed by any of the virtual platforms in the
edk2 repo itself (EmulatorPkg, ArmVirtPkg, OvmfPkg).

This makes sense, but AcpiTableDxe must be added to UefiPayloadPkg's FDF
if patch 2/2 is merged. Otherwise, ACPI tables will not be advertised.