refine pcd comments

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@7800 6f19259b-4bc3-4df7-8a09-765794883524

diff --git a/MdeModulePkg/MdeModulePkg.dec b/MdeModulePkg/MdeModulePkg.dec
index 44962de89ded2a750740eaa5e7bf5f8ab077c925..9aa71b0b6ed64ec749109cbae51a429002448a76 100644 (file)
--- a/MdeModulePkg/MdeModulePkg.dec
+++ b/MdeModulePkg/MdeModulePkg.dec
@@ -221,7 +221,9 @@
   #  It can be disabled to save size.\r
   gEfiMdeModulePkgTokenSpaceGuid.PcdDevicePathSupportDevicePathFromText|TRUE|BOOLEAN|0x00010038\r
     \r
-  ## If TRUE, track statistical information about variable usage stored in the EFI system table.\r
+  ## If TRUE, enable the statistic functionality about variable usage. Such information is\r
+  #  stored as a vendor configuration table into the EFI system table.\r
+  #  If user wants to get variable usage info, this pcd should be set as TRUE.\r
   gEfiMdeModulePkgTokenSpaceGuid.PcdVariableCollectStatistics|FALSE|BOOLEAN|0x0001003f\r
   \r
   ## If TRUE, Unicode Collation Protocol will be installed.\r
@@ -245,7 +247,9 @@
   #  It can be set according to the generated image section type.\r
   gEfiMdeModulePkgTokenSpaceGuid.PcdPeiCoreImageLoaderSearchTeSectionFirst|TRUE|BOOLEAN|0x00010044\r
   \r
-  ## If TRUE, Robustnesss improvement such as for DUET. Default is not required.\r
+  ## If TRUE, force to switch off the support of legacy usb. So legacy usb device driver can not make use of SMI\r
+  #  interrupt to access usb device in the case of absence of usb stack.\r
+  ##\r
   gEfiMdeModulePkgTokenSpaceGuid.PcdTurnOffUsbLegacySupport|FALSE|BOOLEAN|0x00010047\r
 \r
   ## If TRUE, HiiImageProtocol will be installed.\r
@@ -315,13 +319,15 @@
   ## Size of the NV variable range.\r
   gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageVariableSize|0x0|UINT32|0x30000002\r
   \r
-  ## Maximum buffer for the single variable.\r
+  ## Maximum allowable size of a common type variable, that is, non-hardware error type variable.\r
   gEfiMdeModulePkgTokenSpaceGuid.PcdMaxVariableSize|0x400|UINT32|0x30000003\r
   \r
-  ## Maximum buffer for Hardware error record variable.\r
+  ## Maximum allowable size of a single hardware error record variable.\r
   gEfiMdeModulePkgTokenSpaceGuid.PcdMaxHardwareErrorVariableSize|0x8000|UINT32|0x30000004\r
   \r
-  ## Maximum buffer for the total variable store.\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
   gEfiMdeModulePkgTokenSpaceGuid.PcdVariableStoreSize|0x10000|UINT32|0x30000005\r
    \r
   ## Size of the FTW spare block range.\r