Re: Using PcdSet32S for gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageVariableSize

["Gao, Liming" <liming.gao@intel.com>]

You need to configure PCD in [PcdsDynamicDefault.common.DEFAULT] of platform DSC file, and remove it from platform FDF file. 

You can refer to Nt32Pkg\Nt32Pkg.dsc, it configure gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageVariableBase as Dynamic, and set it at boot time. 

Thanks
Liming
> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Vladimir Olovyannikov
> Sent: Friday, March 16, 2018 9:13 AM
> To: edk2-devel@lists.01.org
> Subject: [edk2] Using PcdSet32S for gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageVariableSize
> 
> Hi,
> 
> I would like  to overwrite
> gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageVariableSize
> From an Fvb runtime driver.
> For that purpose I try to do it like this:
> PcdStatus = PcdSet32S(PcdFlashNvStorageVariableBase,
> (UINT32)(UINTN)Instance->VariableBase);
> 
> My .inf file for the driver contains
> [Packages]
>   MdePkg/MdePkg.dec
>   MdeModulePkg/MdeModulePkg.dec
>   MyTestPlatformPkg/MytestPlatformPkg.dec
> 
> and
> [Pcd]
>   gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageVariableSize
> 
> When I build the image, I am getting
> /uefi/MdePkg/Include/Library/PcdLib.h:630:45: error: implicit declaration of
> function `_PCD_SET_MODE_32_S_PcdFlashNvStorageVariableBase`
> [-Werror=implicit-function-declaration]
> #define PcdSet32S(TokenName, Value)         _PCD_SET_MODE_32_S_##TokenName
> ((Value))
>                                              ^
> /uefi/BroadcomPlatformPkg/Drivers/FvbDxe/FvbImpl.c:1090:19: note: in
> expansion of macro `PcdSet32S`
>        PcdStatus = PcdSet32S(PcdFlashNvStorageVariableBase,
> (UINT32)(UINTN)Instance->VariableBase);
>                    ^~~~~~~~~
> in Autogen.h for the driver:
> extern const  UINT32  _gPcd_FixedAtBuild_PcdFlashNvStorageVariableBase;
> #define _PCD_GET_MODE_SIZE_PcdFlashNvStorageVariableBase
> _PCD_SIZE_PcdFlashNvStorageVariableBase
> //#define _PCD_SET_MODE_32_PcdFlashNvStorageVariableBase  ASSERT(FALSE)  //
> It is not allowed to set value for a FIXED_AT_BUILD PCD
> 
> Similarly there are no definitions for other Pcds for PcdSet32 (for instance
> PcdFlashNvStorageFtwWorkingBase);
> they are all set as "FixedAtBuild".
> 
> I can see the PcdFlashNvStorageVariableBase is declared in MdeModulePkg as
> [PcdsFixedAtBuild, PcdsPatchableInModule, PcdsDynamic, PcdsDynamicEx]
> ...
> ## Base address of the NV variable range in flash device.
>   # @Prompt Base address of flash NV variable range.
>   gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageVariableBase|0x0|UINT32|0x30000001
> 
> Why is it set as "FixedAtBuild", and how can I change it to be writable?
> I can see that some platforms (for instance, OvmfPkg) overwrite these
> variables via PcdSet32S/PcdSet64S.
> 
> What am I missing here?
> 
> Thank you,
> Vladimir
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