From 9d39ed931bf59b8d5afdccf7e1c30ece817b7a04 Mon Sep 17 00:00:00 2001 From: Jeff Fan Date: Fri, 18 Dec 2015 03:23:53 +0000 Subject: 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 Cc: Michael Kinney Cc: Jordan Justen Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Jeff Fan Reviewed-by: Michael Kinney git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19342 6f19259b-4bc3-4df7-8a09-765794883524 --- UefiCpuPkg/UefiCpuPkg.dec | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'UefiCpuPkg/UefiCpuPkg.dec') 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.

+ # @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. -- cgit