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

["Zeng, Star" <star.zeng@intel.com>]

It is not been implemented yet. Just for our discussion. I should use future tense in the sentence, sorry.

Thanks,
Star
-----Original Message-----
From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Laszlo Ersek
Sent: Tuesday, March 21, 2017 4:38 PM
To: Zeng, Star <star.zeng@intel.com>; edk2-devel-01 <edk2-devel@lists.01.org>; Kinney, Michael D <michael.d.kinney@intel.com>; Yao, Jiewen <jiewen.yao@intel.com>
Cc: Leif Lindholm <leif.lindholm@linaro.org>; Ard Biesheuvel <ard.biesheuvel@linaro.org>
Subject: Re: [edk2] [PATCH v2 05/12] ArmPkg: introduce EDKII Platform Has ACPI Protocol, and plug-in library

On 03/21/17 03:27, Zeng, Star wrote:
> Just an idea.
> 
> There is a way to do not introduce a new PCD, but reuse PcdAcpiExposedTableVersions.
> When PcdAcpiExposedTableVersions is configured to *0* (means no ANY ACPI table should be exposed), AcpiTableDxe returns EFI_UNSUPPORTED in the driver entrypoint.

Hm, I don't see that:

$ git grep EFI_UNSUPPORTED -- MdeModulePkg/Universal/Acpi/AcpiTableDxe/
[no matches]

Thanks
Laszlo

> 
> 
> Thanks,
> Star
> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of 
> Zeng, Star
> Sent: Monday, March 20, 2017 5:57 PM
> To: Laszlo Ersek <lersek@redhat.com>; edk2-devel-01 
> <edk2-devel@lists.01.org>; Kinney, Michael D 
> <michael.d.kinney@intel.com>; Yao, Jiewen <jiewen.yao@intel.com>
> Cc: Leif Lindholm <leif.lindholm@linaro.org>; Ard Biesheuvel 
> <ard.biesheuvel@linaro.org>
> Subject: Re: [edk2] [PATCH v2 05/12] ArmPkg: introduce EDKII Platform 
> Has ACPI Protocol, and plug-in library
> 
> Oh got it, returning unsuccessfully in constructor of library does not 
> work. :(
> 
> For (1), I definitely have no any comments. :) For (2), I got no strong reason to support or reject it. We'd better could get comments from Mike and Jiewen.
> 
> Thanks,
> Star
> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of 
> Laszlo Ersek
> Sent: Monday, March 20, 2017 5:18 PM
> To: Zeng, Star <star.zeng@intel.com>; edk2-devel-01 
> <edk2-devel@lists.01.org>
> Cc: Leif Lindholm <leif.lindholm@linaro.org>; Ard Biesheuvel 
> <ard.biesheuvel@linaro.org>
> Subject: Re: [edk2] [PATCH v2 05/12] ArmPkg: introduce EDKII Platform 
> Has ACPI Protocol, and plug-in library
> 
> On 03/20/17 03:23, Zeng, Star wrote:
>> Laszlo,
>>
>> Could the implementation have multiple instances of 
>> PlatformHasAcpiLib to return unsuccessfully in the constructor when 
>> EFI_ACPI_TABLE_PROTOCOL is not needed? And then eliminate 
>> PlatformHasAcpiDtDxe, gEdkiiPlatformHasAcpiProtocolGuid and 
>> gEdkiiPlatformHasDeviceTreeProtocolGuid?
> 
> If a library constructor fails, then the client module does not see an explicit error (or automatic unloading); instead, an assertion failure is triggered in auto-generated code.
> 
> For example, in the
> "Build/ArmVirtQemu-AARCH64/DEBUG_GCC5/AARCH64/MdeModulePkg/Universal/Acpi/AcpiTableDxe/AcpiTableDxe/DEBUG/AutoGen.c"
> file, with this series applied, we find:
> 
>> VOID
>> EFIAPI
>> ProcessLibraryConstructorList (
>>   IN EFI_HANDLE        ImageHandle,
>>   IN EFI_SYSTEM_TABLE  *SystemTable
>>   )
>> {
>>   EFI_STATUS  Status;
>>
>>   Status = HobLibConstructor (ImageHandle, SystemTable);
>>   ASSERT_EFI_ERROR (Status);
>>
>>   Status = FdtPL011SerialPortLibInitialize ();
>>   ASSERT_EFI_ERROR (Status);
>>
>>   Status = BaseDebugLibSerialPortConstructor ();
>>   ASSERT_EFI_ERROR (Status);
>>
>>   Status = UefiBootServicesTableLibConstructor (ImageHandle, SystemTable);
>>   ASSERT_EFI_ERROR (Status);
>>
>>   Status = UefiRuntimeServicesTableLibConstructor (ImageHandle, SystemTable);
>>   ASSERT_EFI_ERROR (Status);
>>
>>   Status = UefiLibConstructor (ImageHandle, SystemTable);
>>   ASSERT_EFI_ERROR (Status);
>>
>>   Status = PlatformHasAcpiInitialize (); <--------------- constructor of PlatformHasAcpiLib plug-in lib
>>   ASSERT_EFI_ERROR (Status);
>>
>> }
> 
> What we could do instead would be a new library class, with an explicit initialization function. However, for that to work, AcpiTableDxe would have to be extended with a new library class dependency and a call to the init function. Additionally, out-of-tree platform DSC files would have to resolve this library class to the default instance.
> 
> Introducing a boolean dynamic PCD for the same would be much simpler then; the DEC default would cover out-of-tree platform DSCs without any change in behavior.
> 
> In summary, there are two alternatives in my opinion:
> 
> (1) If we prefer not to modify MdeModulePkg: stick with this series. The only update I'd see justified would be to move gEdkiiPlatformHasDeviceTreeProtocolGuid to EmbeddedPkg as Leif requested.
> 
> (2) If we are willing to modify MdeModulePkg for this problem: introduce a new dynamic PCD such as "PcdAcpiTableEnable", and make AcpiTableDxe exit early if the PCD is FALSE.
> 
> Thanks,
> Laszlo
> 
>>
>> Thanks,
>> Star
>> -----Original Message-----
>> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf 
>> Of Laszlo Ersek
>> Sent: Saturday, March 18, 2017 4:47 AM
>> To: edk2-devel-01 <edk2-devel@lists.01.org>
>> Cc: Leif Lindholm <leif.lindholm@linaro.org>; Ard Biesheuvel 
>> <ard.biesheuvel@linaro.org>
>> Subject: [edk2] [PATCH v2 05/12] ArmPkg: introduce EDKII Platform Has 
>> ACPI Protocol, and plug-in library
>>
>> 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).
>>
>> 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|0x00000
>> 0
>> 01
>>
>> 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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