1 files changed, 36 insertions, 0 deletions
diff --git a/UefiCpuPkg/Include/Library/RegisterCpuFeaturesLib.h b/UefiCpuPkg/Include/Library/RegisterCpuFeaturesLib.h
index be14a92b35..27bd2f6b48 100644
--- a/UefiCpuPkg/Include/Library/RegisterCpuFeaturesLib.h
+++ b/UefiCpuPkg/Include/Library/RegisterCpuFeaturesLib.h
@@ -79,6 +79,37 @@
 /// @}
 
 ///
+/// The bit field to indicate whether the processor is the first in its parent scope.
+///
+typedef struct {
+  //
+  // Set to 1 when current processor is the first thread in the core it resides in.
+  //
+  UINT32 Thread   : 1;
+  //
+  // Set to 1 when current processor is a thread of the first core in the module it resides in.
+  //
+  UINT32 Core     : 1;
+  //
+  // Set to 1 when current processor is a thread of the first module in the tile it resides in.
+  //
+  UINT32 Module   : 1;
+  //
+  // Set to 1 when current processor is a thread of the first tile in the die it resides in.
+  //
+  UINT32 Tile     : 1;
+  //
+  // Set to 1 when current processor is a thread of the first die in the package it resides in.
+  //
+  UINT32 Die      : 1;
+  //
+  // Set to 1 when current processor is a thread of the first package in the system.
+  //
+  UINT32 Package  : 1;
+  UINT32 Reserved : 26;
+} REGISTER_CPU_FEATURE_FIRST_PROCESSOR;
+
+///
 /// CPU Information passed into the SupportFunc and InitializeFunc of the
 /// RegisterCpuFeature() library function.  This structure contains information
 /// that is commonly used during CPU feature detection and initialization.
@@ -88,6 +119,11 @@ typedef struct {
   /// The package that the CPU resides
   ///
   EFI_PROCESSOR_INFORMATION            ProcessorInfo;
+
+  ///
+  /// The bit flag indicating whether the CPU is the first Thread/Core/Module/Tile/Die/Package in its parent scope.
+  ///
+  REGISTER_CPU_FEATURE_FIRST_PROCESSOR First;
   ///
   /// The Display Family of the CPU computed from CPUID leaf CPUID_VERSION_INFO
   ///