1. The original code has a bug on calculate the size of SCRATCH_SIZE. It should be...

[mirror_edk2.git] / MdeModulePkg / MdeModulePkg.dec

diff --git a/MdeModulePkg/MdeModulePkg.dec b/MdeModulePkg/MdeModulePkg.dec
index 366a4be8d905b41a7946b23f1a3c616c9e21119d..a5e348f95bb7e4975ad8bbc77d6d4e850b023693 100644 (file)
--- a/MdeModulePkg/MdeModulePkg.dec
+++ b/MdeModulePkg/MdeModulePkg.dec
@@ -268,21 +268,32 @@
   ## Maximum PPI count is supported by PeiCore's PPI database.\r
   gEfiMdeModulePkgTokenSpaceGuid.PcdPeiCoreMaxPpiSupported|64|UINT32|0x00010033\r
   \r
-  ## Size of the NV variable range.\r
+  ## Size of the NV variable range. Note that this value should less than or equal to PcdFlashNvStorageFtwSpareSize\r
+  # The root cause is that variable driver will use FTW protocol to reclaim variable region.\r
+  # If the length of variable region is larger than FTW spare size, it means the whole variable region can not\r
+  # be reflushed through the manner of fault tolerant write. \r
   gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageVariableSize|0x0|UINT32|0x30000002\r
   \r
-  ## Maximum allowable size of a common type variable, that is, non-hardware error type variable.\r
+  ## The maximum size of single common variable, that is non-HwErr type varible.\r
   gEfiMdeModulePkgTokenSpaceGuid.PcdMaxVariableSize|0x400|UINT32|0x30000003\r
   \r
-  ## Maximum allowable size of a single hardware error record variable.\r
+  ## The maximum size of single hardware error record variable.\r
+  # In IA32/X64 platforms, this value should be larger than 1KB.\r
+  # In IA64 platforms, this value should be larger than 128KB.\r
   gEfiMdeModulePkgTokenSpaceGuid.PcdMaxHardwareErrorVariableSize|0x8000|UINT32|0x30000004\r
   \r
-  ## Size of allocated memory for volatile variable store. Variables are stored in such region and \r
-  #  total length of all variables should not larger than this value.\r
-  ##\r
+  ## The size of reserved HwErr variable space. This space is located at NV variable range.\r
+  # HwErr type variable is stored with common non-volatile variables in NV region.\r
+  # this value is used to guarantee the space of HwErr type variable and not populated by common variable.\r
+  gEfiMdeModulePkgTokenSpaceGuid.PcdHwErrStorageSize|0x8000|UINT32|0x30000006\r
+\r
+  ## The size of volatile buffer. This buffer is used to store VOLATILE attribute variable.\r
   gEfiMdeModulePkgTokenSpaceGuid.PcdVariableStoreSize|0x10000|UINT32|0x30000005\r
-   \r
-  ## Size of the FTW spare block range.\r
+\r
+  ## Size of the FTW spare block range. Note that this value should larger than PcdFlashNvStorageVariableSize\r
+  # The root cause is that variable driver will use FTW protocol to reclaim variable region.\r
+  # If the length of variable region is larger than FTW spare size, it means the whole variable region can not\r
+  # be reflushed through the manner of fault tolerant write.\r
   gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageFtwSpareSize|0x0|UINT32|0x30000014\r
     \r
   ## Size of the FTW working block range.\r