[edk2-devel] [PATCH v2] PcAtChipsetPkg: Fix AcpiTimerLib incompatibility with XhciDxe

["Nate DeSimone" <nathaniel.l.desimone@intel.com>]

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.

Cc: 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>
---
 .../AcpiTimerLib/DxeStandaloneMmAcpiTimerLib.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/PcAtChipsetPkg/Library/AcpiTimerLib/DxeStandaloneMmAcpiTimerLib.c b/PcAtChipsetPkg/Library/AcpiTimerLib/DxeStandaloneMmAcpiTimerLib.c
index 16ac48938f..ccceb8a649 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;
-- 
2.39.2.windows.1



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