From c773514d457265e9ada334572641e1b137c66aac Mon Sep 17 00:00:00 2001
From: Michael Kinney <michael.d.kinney@intel.com>
Date: Thu, 17 Nov 2016 12:43:04 -0800
Subject: [PATCH] UefiCpuPkg/PiSmmCpuDxeSmm: Add volatile to mNumberToFinish

Add volatile qualifier to mNumberToFinish to prevent GCC 5.4
compiler from optimizing away required logic in ACPI S3 resume.

Cc: Liming Gao <liming.gao@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Andrew Fish <afish@apple.com>
Cc: Jeff Fan <jeff.fan@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Michael Kinney <michael.d.kinney@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jeff Fan <jeff.fan@intel.com>
---
 UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c b/UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c
index 4af86b70f2..532b7c44bd 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c
@@ -55,7 +55,7 @@ AsmGetAddressMap (
 #define LEGACY_REGION_BASE    (0xA0000 - LEGACY_REGION_SIZE)
 
 ACPI_CPU_DATA                mAcpiCpuData;
-UINT32                       mNumberToFinish;
+volatile UINT32              mNumberToFinish;
 MP_CPU_EXCHANGE_INFO         *mExchangeInfo;
 BOOLEAN                      mRestoreSmmConfigurationInS3 = FALSE;
 VOID                         *mGdtForAp = NULL;