Re: [EXTERNAL] [edk2-devel][edk2-platforms][PATCH V1 1/1] MinPlatformPkg/Variable*Lib: Build VariableRead and VariableWrite libs

["Bret Barkelew" <bret.barkelew@microsoft.com>]

[-- Attachment #1: Type: text/plain, Size: 8597 bytes --]

Question:

I’ve recently brought up with some that the GetVariable##() functions in UefiLib are probably incorrect as they are written (because they assume things like gRT and gBS availability). Would it perhaps make sense to move this interface up into the MdePkg scope and leverage it to start removing some of those assumptions?

I already have a TODO to start splitting UefiLib along phase lines (PEI, DXE, MM, etc), but that work could largely be obviated with this abstraction.

- Bret

From: Oram, Isaac W via groups.io<mailto:isaac.w.oram=intel.com@groups.io>
Sent: Wednesday, September 8, 2021 3:29 PM
To: devel@edk2.groups.io<mailto:devel@edk2.groups.io>
Cc: Chasel Chiu<mailto:chasel.chiu@intel.com>; Desimone, Nathaniel L<mailto:nathaniel.l.desimone@intel.com>; Liming Gao<mailto:gaoliming@byosoft.com.cn>; Dong, Eric<mailto:eric.dong@intel.com>
Subject: [EXTERNAL] [edk2-devel][edk2-platforms][PATCH V1 1/1] MinPlatformPkg/Variable*Lib: Build VariableRead and VariableWrite libs

Add the VariableReadLib and VariableWriteLib instances to Components to
ensure build when building MinPlatformPkg.dsc.
Add a NULL library instance that provides the non-functional library
instance for VariableReadLib designed for all phase use.

Cc: Chasel Chiu <chasel.chiu@intel.com>
Cc: Nate DeSimone <nathaniel.l.desimone@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Eric Dong <eric.dong@intel.com>
Signed-off-by: Isaac Oram <isaac.w.oram@intel.com>
---
 Platform/Intel/MinPlatformPkg/Library/BaseVariableReadLibNull/BaseVariableReadLibNull.c   | 75 ++++++++++++++++++++
 Platform/Intel/MinPlatformPkg/Library/BaseVariableReadLibNull/BaseVariableReadLibNull.inf | 37 ++++++++++
 Platform/Intel/MinPlatformPkg/MinPlatformPkg.dsc                                          |  6 +-
 3 files changed, 117 insertions(+), 1 deletion(-)

diff --git a/Platform/Intel/MinPlatformPkg/Library/BaseVariableReadLibNull/BaseVariableReadLibNull.c b/Platform/Intel/MinPlatformPkg/Library/BaseVariableReadLibNull/BaseVariableReadLibNull.c
new file mode 100644
index 0000000000..f276b7b6b4
--- /dev/null
+++ b/Platform/Intel/MinPlatformPkg/Library/BaseVariableReadLibNull/BaseVariableReadLibNull.c
@@ -0,0 +1,75 @@
+/** @file
+  NULL implementation of Variable Read Lib
+
+  This library provides phase agnostic access to the UEFI Variable Services.
+  This is done by implementing a wrapper on top of the phase specific mechanism
+  for reading from UEFI variables. For example, the PEI implementation of this
+  library uses EFI_PEI_READ_ONLY_VARIABLE2_PPI. The DXE implementation accesses
+  the UEFI Runtime Services Table, and the SMM implementation uses
+  EFI_SMM_VARIABLE_PROTOCOL.
+
+  Using this library allows code to be written in a generic manner that can be
+  used in PEI, DXE, or SMM without modification.
+
+  @copyright
+  Copyright 2021 Intel Corporation. <BR>
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#include <Uefi/UefiBaseType.h>
+
+/**
+  Returns the value of a variable.
+
+  @param[in]       VariableName  A Null-terminated string that is the name of the vendor's
+                                 variable.
+  @param[in]       VendorGuid    A unique identifier for the vendor.
+  @param[out]      Attributes    If not NULL, a pointer to the memory location to return the
+                                 attributes bitmask for the variable.
+  @param[in, out]  DataSize      On input, the size in bytes of the return Data buffer.
+                                 On output the size of data returned in Data.
+  @param[out]      Data          The buffer to return the contents of the variable. May be NULL
+                                 with a zero DataSize in order to determine the size buffer needed.
+
+  @retval EFI_UNSUPPORTED        This function is not implemented by this instance of the LibraryClass
+
+**/
+EFI_STATUS
+EFIAPI
+VarLibGetVariable (
+  IN     CHAR16                      *VariableName,
+  IN     EFI_GUID                    *VendorGuid,
+  OUT    UINT32                      *Attributes,    OPTIONAL
+  IN OUT UINTN                       *DataSize,
+  OUT    VOID                        *Data           OPTIONAL
+  )
+{
+  return EFI_UNSUPPORTED;
+}
+
+/**
+  Enumerates the current variable names.
+
+  @param[in, out]  VariableNameSize The size of the VariableName buffer. The size must be large
+                                    enough to fit input string supplied in VariableName buffer.
+  @param[in, out]  VariableName     On input, supplies the last VariableName that was returned
+                                    by GetNextVariableName(). On output, returns the Nullterminated
+                                    string of the current variable.
+  @param[in, out]  VendorGuid       On input, supplies the last VendorGuid that was returned by
+                                    GetNextVariableName(). On output, returns the
+                                    VendorGuid of the current variable.
+
+  @retval EFI_UNSUPPORTED           This function is not implemented by this instance of the LibraryClass
+
+**/
+EFI_STATUS
+EFIAPI
+VarLibGetNextVariableName (
+  IN OUT UINTN                    *VariableNameSize,
+  IN OUT CHAR16                   *VariableName,
+  IN OUT EFI_GUID                 *VendorGuid
+  )
+{
+  return EFI_UNSUPPORTED;
+}
diff --git a/Platform/Intel/MinPlatformPkg/Library/BaseVariableReadLibNull/BaseVariableReadLibNull.inf b/Platform/Intel/MinPlatformPkg/Library/BaseVariableReadLibNull/BaseVariableReadLibNull.inf
new file mode 100644
index 0000000000..3a397998a9
--- /dev/null
+++ b/Platform/Intel/MinPlatformPkg/Library/BaseVariableReadLibNull/BaseVariableReadLibNull.inf
@@ -0,0 +1,37 @@
+## @file
+# Component description file for NULL implementation of Variable Read Lib
+#
+# This library provides phase agnostic access to the UEFI Variable Services.
+# This is done by implementing a wrapper on top of the phase specific mechanism
+# for reading from UEFI variables. For example, the PEI implementation of this
+# library uses EFI_PEI_READ_ONLY_VARIABLE2_PPI. The DXE implementation accesses
+# the UEFI Runtime Services Table, and the SMM implementation uses
+# EFI_SMM_VARIABLE_PROTOCOL.
+#
+# Using this library allows code to be written in a generic manner that can be
+# used in PEI, DXE, or SMM without modification.
+#
+# @copyright
+# Copyright 2021 Intel Corporation. <BR>
+#
+# SPDX-License-Identifier: BSD-2-Clause-Patent
+##
+
+##
+## NOTICE: This library is also available in MinPlatformPkg. This copy was added
+##         for the convience of those that are using an older MinPlatformPkg.
+##
+
+[Defines]
+  INF_VERSION                    = 0x00010005
+  BASE_NAME                      = BaseVariableReadLibNull
+  FILE_GUID                      = 5C9E2489-329F-4D2A-90F1-F5CB2A88A3E6
+  VERSION_STRING                 = 1.0
+  MODULE_TYPE                    = BASE
+  LIBRARY_CLASS                  = VariableReadLib
+
+[Packages]
+  MdePkg/MdePkg.dec
+
+[Sources]
+  BaseVariableReadLibNull.c
diff --git a/Platform/Intel/MinPlatformPkg/MinPlatformPkg.dsc b/Platform/Intel/MinPlatformPkg/MinPlatformPkg.dsc
index 07b776cecd..a09f8db3ab 100644
--- a/Platform/Intel/MinPlatformPkg/MinPlatformPkg.dsc
+++ b/Platform/Intel/MinPlatformPkg/MinPlatformPkg.dsc
@@ -74,7 +74,7 @@
   FspWrapperApiTestLib|IntelFsp2WrapperPkg/Library/PeiFspWrapperApiTestLib/PeiFspWrapperApiTestLib.inf
   FspWrapperHobProcessLib|MinPlatformPkg/FspWrapper/Library/PeiFspWrapperHobProcessLib/PeiFspWrapperHobProcessLib.inf
   PlatformSecLib|MinPlatformPkg/FspWrapper/Library/SecFspWrapperPlatformSecLib/SecFspWrapperPlatformSecLib.inf
-
+  VariableReadLib|MinPlatformPkg/Library/BaseVariableReadLibNull/BaseVariableReadLibNull.inf
   FspWrapperPlatformLib|MinPlatformPkg/FspWrapper/Library/PeiFspWrapperPlatformLib/PeiFspWrapperPlatformLib.inf

   BoardInitLib|MinPlatformPkg/PlatformInit/Library/BoardInitLibNull/BoardInitLibNull.inf
@@ -214,5 +214,9 @@
   MinPlatformPkg/Tcg/Tcg2PlatformPei/Tcg2PlatformPei.inf
   MinPlatformPkg/Tcg/Tcg2PlatformDxe/Tcg2PlatformDxe.inf

+  MinPlatformPkg/Library/BaseVariableReadLibNull/BaseVariableReadLibNull.inf
+  MinPlatformPkg/Library/SmmVariableReadLib/StandaloneMmVariableReadLib.inf
+  MinPlatformPkg/Library/SmmVariableWriteLib/StandaloneMmVariableWriteLib.inf
+
 [BuildOptions]
   *_*_*_CC_FLAGS = -D DISABLE_NEW_DEPRECATED_INTERFACES
--
2.27.0.windows.1







[-- Attachment #2: Type: text/html, Size: 15308 bytes --]