Re: [edk2-devel] [Patch V2 0/2] Let AcpiTableDxe driver install Acpi table from Hob

["Laszlo Ersek" <lersek@redhat.com>]

On 03/24/21 17:55, Benjamin Doron wrote:
>>
>>
>>> 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.

But this is already the best approach, and already what's happening --
when you call EFI_ACPI_TABLE_PROTOCOL.InstallAcpiTable() from the
platform's AcpiPlatformDxe, that's *how* you tell AcpiTableDxe in
MdeModulePkg to pick up the table and hook it into the RSDT / XSDT /
wherever, and also to manage RSD PTR as a UEFI configuration table.

Are you (more or less) proposing a new EFI_ACPI_TABLE_PROTOCOL member
function for taking a forest of ACPI tables, passed in by RSD PTR?

Sorry about being dense. :)

> (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.
> 

Good point; I missed that. (I'm not familiar with the UefiPayloadPkg FDF
at all.)

Laszlo