Re: [PATCH v2 05/12] ArmPkg: introduce EDKII Platform Has ACPI Protocol, and plug-in library

[Laszlo Ersek <lersek@redhat.com>]

On 03/18/17 16:00, Leif Lindholm wrote:
> On Fri, Mar 17, 2017 at 09:47:24PM +0100, Laszlo Ersek wrote:
>> The presence of this protocol in the DXE protocol database implies that
>> the platform provides the operating system with an ACPI-based hardware
>> description. This is not necessarily mutually exclusive with a Device
>> Tree-based hardware description. A platform driver is supposed to produce
>> a single instance of the protocol (with NULL contents), if appropriate.
>>
>> The decision to produce the protocol is platform specific; for example, it
>> could depend on an HII checkbox / underlying non-volatile UEFI variable.
>>
>> The protocol is meant to be consumed by
>> "MdeModulePkg/Universal/Acpi/AcpiTableDxe", through the
>> PlatformHasAcpiLib plug-in. By linking this library into AcpiTableDxe via
>> NULL resolution in the platform DSC, the platform makes
>> EFI_ACPI_TABLE_PROTOCOL and (if enabled) EFI_ACPI_SDT_PROTOCOL dependent
>> on the above dynamic decision.
>>
>> In turn, other (platform and universal) DXE drivers that produce ACPI
>> tables will wait for EFI_ACPI_TABLE_PROTOCOL / EFI_ACPI_SDT_PROTOCOL, via
>> DEPEX, protocol notify, or a simple gBS->LocateProtocol() in a "late
>> enough" callback (such as Ready To Boot).
>>
>> Because this protocol is not standard, it is prefixed with EDKII / Edkii,
>> as seen elsewhere in MdeModulePkg and SecurityPkg, for example. (ARM / Arm
>> doesn't look future-proof enough; future UEFI platforms could face the
>> same issue.) In addition, an effort is made to avoid the phrase
>> "AcpiPlatform", as that belongs to drivers / libraries that produce
>> platform specific ACPI content (as opposed to deciding whether the entire
>> firmware will have access to EFI_ACPI_TABLE_PROTOCOL).
> 
> I greatly approve, but since you've already done this generically - is
> there any good reason to keep this in ArmPkg?
> I am strongly looking to get rid of "things that happen to have been
> implemented for ARM" from there and pruning it down to contain only
> things that are architecturelly ARM-specific.
> 
> MdeModulePkg?

It looks like Ard is okay with this series after all, and you (Leif)
also seem to tolerate it. The question is now if the MdeModulePkg owners
are okay to take this patch for MdeModulePkg.

Star, Feng, can I add the protocol definition and the library instance
in this patch to MdeModulePkg? (We've ruled out the dynamic PCD
discussed previously for AcpiTableDxe, because platforms would have even
greater trouble setting such a PCD than using this protocol.)

Can you guys please give a decisive answer in one or two days?

Thank you,
Laszlo


> 
> Regards,
> 
> Leif
> 
>> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>> Cc: Leif Lindholm <leif.lindholm@linaro.org>
>> Contributed-under: TianoCore Contribution Agreement 1.0
>> Signed-off-by: Laszlo Ersek <lersek@redhat.com>
>> ---
>>  ArmPkg/ArmPkg.dec                                        |  4 ++
>>  ArmPkg/Library/PlatformHasAcpiLib/PlatformHasAcpiLib.inf | 40 ++++++++++++++++++++
>>  ArmPkg/Include/Protocol/PlatformHasAcpi.h                | 34 +++++++++++++++++
>>  ArmPkg/Library/PlatformHasAcpiLib/PlatformHasAcpiLib.c   | 36 ++++++++++++++++++
>>  4 files changed, 114 insertions(+)
>>
>> diff --git a/ArmPkg/ArmPkg.dec b/ArmPkg/ArmPkg.dec
>> index c4b4da2f95bb..0e49360a386a 100644
>> --- a/ArmPkg/ArmPkg.dec
>> +++ b/ArmPkg/ArmPkg.dec
>> @@ -52,6 +52,10 @@ [Ppis]
>>    ## Include/Ppi/ArmMpCoreInfo.h
>>    gArmMpCoreInfoPpiGuid = { 0x6847cc74, 0xe9ec, 0x4f8f, {0xa2, 0x9d, 0xab, 0x44, 0xe7, 0x54, 0xa8, 0xfc} }
>>  
>> +[Protocols]
>> +  ## Include/Protocol/PlatformHasAcpi.h
>> +  gEdkiiPlatformHasAcpiProtocolGuid =       { 0xf0966b41, 0xc23f, 0x41b9, { 0x96, 0x04, 0x0f, 0xf7, 0xe1, 0x11, 0x96, 0x5a } }
>> +
>>  [PcdsFeatureFlag.common]
>>    gArmTokenSpaceGuid.PcdCpuDxeProduceDebugSupport|FALSE|BOOLEAN|0x00000001
>>  
>> diff --git a/ArmPkg/Library/PlatformHasAcpiLib/PlatformHasAcpiLib.inf b/ArmPkg/Library/PlatformHasAcpiLib/PlatformHasAcpiLib.inf
>> new file mode 100644
>> index 000000000000..c83da4d8e98a
>> --- /dev/null
>> +++ b/ArmPkg/Library/PlatformHasAcpiLib/PlatformHasAcpiLib.inf
>> @@ -0,0 +1,40 @@
>> +## @file
>> +# A hook-in library for MdeModulePkg/Universal/Acpi/AcpiTableDxe.
>> +#
>> +# Plugging this library instance into AcpiTableDxe makes
>> +# EFI_ACPI_TABLE_PROTOCOL and (if enabled) EFI_ACPI_SDT_PROTOCOL depend on the
>> +# platform's dynamic decision whether to expose an ACPI-based hardware
>> +# description to the operating system.
>> +#
>> +# Universal and platform specific DXE drivers that produce ACPI tables depend
>> +# on EFI_ACPI_TABLE_PROTOCOL / EFI_ACPI_SDT_PROTOCOL in turn.
>> +#
>> +# Copyright (C) 2017, Red Hat, Inc.
>> +#
>> +# This program and the accompanying materials are licensed and made available
>> +# under the terms and conditions of the BSD License which accompanies this
>> +# distribution. The full text of the license may be found at
>> +# http://opensource.org/licenses/bsd-license.php
>> +#
>> +# THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT
>> +# WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>> +##
>> +
>> +[Defines]
>> +  INF_VERSION                    = 1.25
>> +  BASE_NAME                      = PlatformHasAcpiLib
>> +  FILE_GUID                      = 29beb028-0958-447b-be0a-12229235d77d
>> +  MODULE_TYPE                    = BASE
>> +  VERSION_STRING                 = 1.0
>> +  LIBRARY_CLASS                  = PlatformHasAcpiLib|DXE_DRIVER
>> +  CONSTRUCTOR                    = PlatformHasAcpiInitialize
>> +
>> +[Sources]
>> +  PlatformHasAcpiLib.c
>> +
>> +[Packages]
>> +  ArmPkg/ArmPkg.dec
>> +  MdePkg/MdePkg.dec
>> +
>> +[Depex]
>> +  gEdkiiPlatformHasAcpiProtocolGuid
>> diff --git a/ArmPkg/Include/Protocol/PlatformHasAcpi.h b/ArmPkg/Include/Protocol/PlatformHasAcpi.h
>> new file mode 100644
>> index 000000000000..3cd0cfe4515d
>> --- /dev/null
>> +++ b/ArmPkg/Include/Protocol/PlatformHasAcpi.h
>> @@ -0,0 +1,34 @@
>> +/** @file
>> +  EDKII Platform Has ACPI Protocol
>> +
>> +  The presence of this protocol in the DXE protocol database implies that the
>> +  platform provides the operating system with an ACPI-based hardware
>> +  description. Note that this is not necessarily mutually exclusive with a
>> +  Device Tree-based hardware description. A platform driver is supposed to
>> +  produce a single instance of the protocol (with NULL contents), if
>> +  appropriate.
>> +
>> +  Copyright (C) 2017, Red Hat, Inc.
>> +
>> +  This program and the accompanying materials are licensed and made available
>> +  under the terms and conditions of the BSD License that accompanies this
>> +  distribution. The full text of the license may be found at
>> +  http://opensource.org/licenses/bsd-license.php.
>> +
>> +  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT
>> +  WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>> +**/
>> +
>> +
>> +#ifndef __EDKII_PLATFORM_HAS_ACPI_PROTOCOL_H__
>> +#define __EDKII_PLATFORM_HAS_ACPI_PROTOCOL_H__
>> +
>> +#define EDKII_PLATFORM_HAS_ACPI_PROTOCOL_GUID \
>> +  { \
>> +    0xf0966b41, 0xc23f, 0x41b9, \
>> +    { 0x96, 0x04, 0x0f, 0xf7, 0xe1, 0x11, 0x96, 0x5a } \
>> +  }
>> +
>> +extern EFI_GUID gEdkiiPlatformHasAcpiProtocolGuid;
>> +
>> +#endif
>> diff --git a/ArmPkg/Library/PlatformHasAcpiLib/PlatformHasAcpiLib.c b/ArmPkg/Library/PlatformHasAcpiLib/PlatformHasAcpiLib.c
>> new file mode 100644
>> index 000000000000..79072da21c2b
>> --- /dev/null
>> +++ b/ArmPkg/Library/PlatformHasAcpiLib/PlatformHasAcpiLib.c
>> @@ -0,0 +1,36 @@
>> +/** @file
>> +  A hook-in library for MdeModulePkg/Universal/Acpi/AcpiTableDxe.
>> +
>> +  Plugging this library instance into AcpiTableDxe makes
>> +  EFI_ACPI_TABLE_PROTOCOL and (if enabled) EFI_ACPI_SDT_PROTOCOL depend on the
>> +  platform's dynamic decision whether to expose an ACPI-based hardware
>> +  description to the operating system.
>> +
>> +  Universal and platform specific DXE drivers that produce ACPI tables depend
>> +  on EFI_ACPI_TABLE_PROTOCOL / EFI_ACPI_SDT_PROTOCOL in turn.
>> +
>> +  Copyright (C) 2017, Red Hat, Inc.
>> +
>> +  This program and the accompanying materials are licensed and made available
>> +  under the terms and conditions of the BSD License which accompanies this
>> +  distribution. The full text of the license may be found at
>> +  http://opensource.org/licenses/bsd-license.php
>> +
>> +  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT
>> +  WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>> +**/
>> +
>> +#include <Base.h>
>> +
>> +RETURN_STATUS
>> +EFIAPI
>> +PlatformHasAcpiInitialize (
>> +  VOID
>> +  )
>> +{
>> +  //
>> +  // Do nothing, just imbue AcpiTableDxe with an
>> +  // EDKII_PLATFORM_HAS_ACPI_PROTOCOL dependency.
>> +  //
>> +  return RETURN_SUCCESS;
>> +}
>> -- 
>> 2.9.3
>>
>>
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