Re: [edk2-devel] [PATCH v1] PcAtChipsetPkg: Fix AcpiTimerLib incompatibility with XhciDxe

["Ni, Ray" <ray.ni@intel.com>]

Mike,
Does today's EDK2 C coding style spec allow using "STATIC" for global variables?
Or lower case "static"?
Or changing the variable to a name with lib name prefix, e.g.: " mTimerLibPerformanceCounterFrequency"?


Thanks,
Ray
> -----Original Message-----
> From: Desimone, Nathaniel L <nathaniel.l.desimone@intel.com>
> Sent: Friday, December 1, 2023 9:56 AM
> To: devel@edk2.groups.io
> Cc: Ni, Ray <ray.ni@intel.com>; Kinney, Michael D
> <michael.d.kinney@intel.com>
> Subject: [PATCH v1] 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. 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>
> ---
>  .../Library/AcpiTimerLib/DxeStandaloneMmAcpiTimerLib.c        | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git
> a/PcAtChipsetPkg/Library/AcpiTimerLib/DxeStandaloneMmAcpiTimerLib.c
> b/PcAtChipsetPkg/Library/AcpiTimerLib/DxeStandaloneMmAcpiTimerLib.c
> index 16ac48938f..41d2af7d55 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
> 
>  **/
> @@ -51,7 +51,7 @@ InternalCalculateTscFrequency (
>  //
>  // Cached performance counter frequency
>  //
> -UINT64  mPerformanceCounterFrequency = 0;
> +STATIC UINT64 mPerformanceCounterFrequency = 0;
> 
>  /**
>    Internal function to retrieves the 64-bit frequency in Hz.
> --
> 2.39.2.windows.1



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