From df2ec2aab0876d34025968030d1f26ad8e5106ec Mon Sep 17 00:00:00 2001
From: Nate DeSimone <nathaniel.l.desimone@intel.com>
Date: Thu, 30 Nov 2023 17:33:14 -0800
Subject: PcAtChipsetPkg: Fix AcpiTimerLib incompatibility with XhciDxe

The DXE & MM standalone variant of AcpiTimerLib defines a global
named mPerformanceCounterFrequency. A global with an identical
name is also present in MdeModulePkg/Bus/Pci/XhciDxe/Xhci.c

Since XhciDxe has a dependency on TimerLib, this can cause link
errors due to the same symbol being defined twice if the platform
DSC chooses to use AcpiTimerLib as the TimerLib implementation for
any given platform.

To resolve this, I have changed made the definition of
mPerformanceCounterFrequency to static and renamed it to
mAcpiTimerLibTscFrequency. Since this variable is not used outside
of the DxeStandaloneMmAcpiTimerLib.c compilation unit, there is no
reason to have it exported as a global.

Reviewed-by: Ray Ni <ray.ni@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Signed-off-by: Nate DeSimone <nathaniel.l.desimone@intel.com>
---
 .../Library/AcpiTimerLib/DxeStandaloneMmAcpiTimerLib.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

(limited to 'PcAtChipsetPkg')

diff --git a/PcAtChipsetPkg/Library/AcpiTimerLib/DxeStandaloneMmAcpiTimerLib.c b/PcAtChipsetPkg/Library/AcpiTimerLib/DxeStandaloneMmAcpiTimerLib.c
index 16ac48938f..ccb43a283e 100644
--- a/PcAtChipsetPkg/Library/AcpiTimerLib/DxeStandaloneMmAcpiTimerLib.c
+++ b/PcAtChipsetPkg/Library/AcpiTimerLib/DxeStandaloneMmAcpiTimerLib.c
@@ -1,7 +1,7 @@
 /** @file
   ACPI Timer implements one instance of Timer Library.
 
-  Copyright (c) 2013 - 2018, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2013 - 2023, Intel Corporation. All rights reserved.<BR>
   SPDX-License-Identifier: BSD-2-Clause-Patent
 
 **/
@@ -11,6 +11,11 @@
 #include <Library/BaseLib.h>
 #include <Library/HobLib.h>
 
+//
+// Cached performance counter frequency
+//
+static UINT64  mAcpiTimerLibTscFrequency = 0;
+
 extern GUID  mFrequencyHobGuid;
 
 /**
@@ -48,11 +53,6 @@ InternalCalculateTscFrequency (
   VOID
   );
 
-//
-// Cached performance counter frequency
-//
-UINT64  mPerformanceCounterFrequency = 0;
-
 /**
   Internal function to retrieves the 64-bit frequency in Hz.
 
@@ -66,7 +66,7 @@ InternalGetPerformanceCounterFrequency (
   VOID
   )
 {
-  return mPerformanceCounterFrequency;
+  return mAcpiTimerLibTscFrequency;
 }
 
 /**
@@ -92,9 +92,9 @@ CommonAcpiTimerLibConstructor (
   //
   GuidHob = GetFirstGuidHob (&mFrequencyHobGuid);
   if (GuidHob != NULL) {
-    mPerformanceCounterFrequency = *(UINT64 *)GET_GUID_HOB_DATA (GuidHob);
+    mAcpiTimerLibTscFrequency = *(UINT64 *)GET_GUID_HOB_DATA (GuidHob);
   } else {
-    mPerformanceCounterFrequency = InternalCalculateTscFrequency ();
+    mAcpiTimerLibTscFrequency = InternalCalculateTscFrequency ();
   }
 
   return EFI_SUCCESS;
-- 
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