refine VariablePei driver to unify the algorithm of access VariableIndexTable among various archs.

1. record the distance of two neighboring VAR_ADDED type variables rather than the offset of each variable. As the field recording this info is UINT16 width, the latter causes in IA32/X64 platform, it can only cache those variables from offset 0 to offset 2^16; in IPF platform, from offset 0 to offset 2^18(extend the scope by left-shift the offset two bits).
when taking the former algorithm, the max range of caching variable is from offset 0 to offset 122*(2^16)

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@8625 6f19259b-4bc3-4df7-8a09-765794883524

1 files changed, 38 insertions, 6 deletions

diff --git a/MdeModulePkg/Universal/Variable/Pei/Variable.c b/MdeModulePkg/Universal/Variable/Pei/Variable.c
index 39998f5f67..4716eac9ec 100644
--- a/MdeModulePkg/Universal/Variable/Pei/Variable.c
+++ b/MdeModulePkg/Universal/Variable/Pei/Variable.c
@@ -366,10 +366,13 @@ FindVariable (
   EFI_HOB_GUID_TYPE       *GuidHob;

   VARIABLE_STORE_HEADER   *VariableStoreHeader;

   VARIABLE_HEADER         *Variable;

+  VARIABLE_HEADER         *LastVariable;

   VARIABLE_HEADER         *MaxIndex;

   VARIABLE_INDEX_TABLE    *IndexTable;

   UINT32                  Count;

+  UINT32                  Offset;

   UINT8                   *VariableBase;

+  BOOLEAN                 StopRecord;

 

   if (VariableName[0] != 0 && VendorGuid == NULL) {

     return EFI_INVALID_PARAMETER;

@@ -378,9 +381,16 @@ FindVariable (
   // No Variable Address equals zero, so 0 as initial value is safe.

   //

   MaxIndex = 0;

+  StopRecord = FALSE;

 

   GuidHob = GetFirstGuidHob (&mEfiVariableIndexTableGuid);

   if (GuidHob == NULL) {

+    //

+    // If it's the first time to access variable region in flash, create a guid hob to record

+    // VAR_ADDED type variable info.

+    // Note that as the resource of PEI phase is limited, only store the number of 

+    // VARIABLE_INDEX_TABLE_VOLUME of VAR_ADDED type variables to reduce access time.

+    //

     IndexTable = BuildGuidHob (&mEfiVariableIndexTableGuid, sizeof (VARIABLE_INDEX_TABLE));

     IndexTable->Length      = 0;

     IndexTable->StartPtr    = NULL;

@@ -388,9 +398,13 @@ FindVariable (
     IndexTable->GoneThrough = 0;

   } else {

     IndexTable = GET_GUID_HOB_DATA (GuidHob);

-    for (Count = 0; Count < IndexTable->Length; Count++) {

-      MaxIndex = GetVariableByIndex (IndexTable, Count);

-

+    for (Offset = 0, Count = 0; Count < IndexTable->Length; Count++) {

+      //

+      // traverse the variable info list to look for varible.

+      // The IndexTable->Index[Count] records the distance of two neighbouring VAR_ADDED type variables.

+      //

+      Offset   += IndexTable->Index[Count];

+      MaxIndex  = (VARIABLE_HEADER *)((CHAR8 *)(IndexTable->StartPtr) + Offset);

       if (CompareWithValidVariable (MaxIndex, VariableName, VendorGuid, PtrTrack) == EFI_SUCCESS) {

         PtrTrack->StartPtr  = IndexTable->StartPtr;

         PtrTrack->EndPtr    = IndexTable->EndPtr;

@@ -407,7 +421,8 @@ FindVariable (
   // If not found in HOB, then let's start from the MaxIndex we've found.

   //

   if (MaxIndex != NULL) {

-    Variable = GetNextVariablePtr (MaxIndex);

+    Variable     = GetNextVariablePtr (MaxIndex);

+    LastVariable = MaxIndex;

   } else {

     if ((IndexTable->StartPtr != NULL) || (IndexTable->EndPtr != NULL)) {

       Variable = IndexTable->StartPtr;

@@ -435,6 +450,8 @@ FindVariable (
       //

       Variable = IndexTable->StartPtr;

     }

+

+    LastVariable = IndexTable->StartPtr;

   }

   //

   // Find the variable by walk through non-volatile variable store

@@ -447,8 +464,23 @@ FindVariable (
       //

       // Record Variable in VariableIndex HOB

       //

-      VariableIndexTableUpdate (IndexTable, Variable);

-      

+      if (IndexTable->Length < VARIABLE_INDEX_TABLE_VOLUME && StopRecord != TRUE) {

+        Offset = (UINT32)((UINTN)Variable - (UINTN)LastVariable);

+        //

+        // The distance of two neighbouring VAR_ADDED variable is larger than 2^16, 

+        // which is beyond the allowable scope(UINT16) of record. In such case, need not to

+        // record the subsequent VAR_ADDED type variables again.

+        //

+        if ((Offset & 0xFFFF0000UL) != 0) {

+          StopRecord = TRUE;

+        }

+

+        if (StopRecord != TRUE) {

+          IndexTable->Index[IndexTable->Length++] = (UINT16) Offset;

+        }

+        LastVariable = Variable;

+      }

+

       if (CompareWithValidVariable (Variable, VariableName, VendorGuid, PtrTrack) == EFI_SUCCESS) {

         return EFI_SUCCESS;

       }