From 9d39ed931bf59b8d5afdccf7e1c30ece817b7a04 Mon Sep 17 00:00:00 2001
From: Jeff Fan <jeff.fan@intel.com>
Date: Fri, 18 Dec 2015 03:23:53 +0000
Subject: [PATCH] UefiCpuPkg: Add PCD PcdCpuApTargetCstate

This new PCD is used to specify the AP C-state value by MWAIT instruction.

More deeper C-state means more longer latency time when APs exiting from MWAIT
state. Platforms need to balance the performance and power saving to find the
proper C-state for APs.

Also, some processor may not ready for the deepest C-state at the beginning.
Platform also could choose the proper chance to place AP into the deeper C-state
by set this PCD before hand-off to OS.

Contributed-under: TianoCore Contribution Agreement 1.0
Cc: Feng Tian <feng.tian@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jeff Fan <jeff.fan@intel.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19342 6f19259b-4bc3-4df7-8a09-765794883524
---
 UefiCpuPkg/UefiCpuPkg.dec | 5 +++++
 UefiCpuPkg/UefiCpuPkg.uni | 4 ++++
 2 files changed, 9 insertions(+)

diff --git a/UefiCpuPkg/UefiCpuPkg.dec b/UefiCpuPkg/UefiCpuPkg.dec
index 0d42918427..472b38acbc 100644
--- a/UefiCpuPkg/UefiCpuPkg.dec
+++ b/UefiCpuPkg/UefiCpuPkg.dec
@@ -190,6 +190,11 @@
   # @Prompt The AP wait loop state.
   # @ValidRange  0x80000001 | 1 - 3
   gUefiCpuPkgTokenSpaceGuid.PcdCpuApLoopMode|1|UINT8|0x60008006
+  ## Specifies the AP target C-state for Mwait during POST phase.
+  #  The default value 0 means C1 state.
+  #  The value is defined as below.<BR><BR>
+  # @Prompt The specified AP target C-state for Mwait.
+  gUefiCpuPkgTokenSpaceGuid.PcdCpuApTargetCstate|0|UINT8|0x00000007
 
 [PcdsDynamic, PcdsDynamicEx]
   ## Contains the pointer to a CPU S3 data buffer of structure ACPI_CPU_DATA.
diff --git a/UefiCpuPkg/UefiCpuPkg.uni b/UefiCpuPkg/UefiCpuPkg.uni
index 2c74a92e06..13f0e41aeb 100644
--- a/UefiCpuPkg/UefiCpuPkg.uni
+++ b/UefiCpuPkg/UefiCpuPkg.uni
@@ -143,3 +143,7 @@
 
 #string STR_gUefiCpuPkgTokenSpaceGuid_PcdCpuApLoopMode_HELP  #language en-US "Specifies the AP wait loop state during POST phase."
 
+#string STR_gUefiCpuPkgTokenSpaceGuid_PcdCpuApTargetCstate_PROMPT  #language en-US "The specified AP target C-state for Mwait"
+
+#string STR_gUefiCpuPkgTokenSpaceGuid_PcdCpuApTargetCstate_HELP  #language en-US "Specifies the AP target C-state for Mwait during POST phase."
+