From mboxrd@z Thu Jan  1 00:00:00 1970
Subject: Re: [edk2-devel] [Patch V2 0/2] Let AcpiTableDxe driver install Acpi table from Hob
To: Laszlo Ersek <lersek@redhat.com>,devel@edk2.groups.io
From: "Benjamin Doron" <benjamin.doron00@gmail.com>
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Date: Wed, 24 Mar 2021 09:55:28 -0700
References: <8ecc6ec1-f7a0-7878-ef57-b58f99bc3af2@redhat.com>
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>=20
>=20
>> 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 RSD=
P
>> is in the configuration table, we probably always want those tables).
>=20
> I'm sorry, I don't understand how this would help.

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

Perhaps it would be an acceptable solution for platforms to retrieve the t=
ables, then add
RSDP/them to the configuration table to be installed by AcpiTableDxe/AcpiP=
latformDxe.
This allows MdeModulePkg to abstract away the parsing, only installing tab=
les
available to it.
(Currently, UefiPayloadPkg's BlSupportDxe retrieves the data from a HOB an=
d calls
`gBS->InstallConfigurationTable` with the address of RSDP).

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

>=20
>=20
>> 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?
>=20
> 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.

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<blockquote>
<blockquote>Hi all,<br />Would it be acceptable/feasible for AcpiTableDxe =
or AcpiPlatformDxe (in<br />MdeModulePkg) to use `EfiGetSystemConfiguration=
Table` to get the RSDP<br />and then install the tables? It's a solution th=
at uses the regular<br />UefiLib, so it avoids platform-specific quirks (an=
d as I see it, if RSDP<br />is in the configuration table, we probably alwa=
ys want those tables).</blockquote>
I'm sorry, I don't understand how this would help.</blockquote>
As I understand it, the issue is that this patchset changes MdeModulePkg t=
o do platform-specific parsing.<br /><br />Perhaps it would be an acceptabl=
e solution for platforms to retrieve the tables, then add<br />RSDP/them to=
 the configuration table to be installed by AcpiTableDxe/AcpiPlatformDxe.<b=
r />This allows MdeModulePkg to abstract away the parsing, only installing =
tables<br />available to it.<br />(Currently, UefiPayloadPkg's BlSupportDxe=
 retrieves the data from a HOB and calls<br />`gBS-&gt;InstallConfiguration=
Table` with the address of RSDP).<br /><br />I understand that this may not=
 work for OVMF if tables are located differently in memory.<br />
<blockquote>
<blockquote>Regarding UefiPayloadPkg: AcpiTableDxe is currently compiled (=
listed in<br />DSC) but not added to a FV (not listed in FDF). So, how has =
this been<br />tested?</blockquote>
I assume through an out-of-tree platform. Many such core modules exist<br =
/>in edk2 that are not consumed by any of the virtual platforms in the<br /=
>edk2 repo itself (EmulatorPkg, ArmVirtPkg, OvmfPkg).</blockquote>
This makes sense, but AcpiTableDxe must be added to UefiPayloadPkg's FDF<b=
r />if patch 2/2 is merged. Otherwise, ACPI tables will not be advertised.

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