Re: [edk2-devel] [PATCH edk2-platforms 2/2] SbsaQemu: set CPU model in SMBIOS

["Nhi Pham via groups.io" <nhi=os.amperecomputing.com@groups.io>]

On 7/12/2024 5:01 PM, Ard Biesheuvel via groups.io wrote:
> On Fri, 12 Jul 2024 at 11:24, Marcin Juszkiewicz
> <marcin.juszkiewicz@linaro.org> wrote:
>>
>> SbsaQemu platform have several cpu models available. Since start it
>> reported "arm-virt" one in SMBIOS instead of real one.
>>
>> This change replaces it with the real cpu model like Cortex-A57,
>> Neoverse-N2 etc.
>>
>> Requires change in EDK2 to make PcdProcessorVersion dynamic.
>>
>> Signed-off-by: Marcin Juszkiewicz <marcin.juszkiewicz@linaro.org>
> 
> I am going to make the same remark as I did before in a different
> context: how is it guaranteed that the code that sets the PCD executes
> before the code that consumes it?

We could implement the setting in a 'PlatformInitDxe', which will be 
added to the 'APPRIORI DXE' list to ensure it is scheduled to run in the 
early DXE phase. This approach will help initialize the neccessary 
compoenents early in the DXE phase, providing a stable foundation for 
subsequent operations.

> 
> Making PCDs dynamic is usually not the solution here, unless they are
> set in the PEI phase and consumed in the DXE phase or after.
> 
> The EFI SMBIOS protocol has an 'update string' method that you can
> call from a platform driver. That might be a better fit here, and the
> PCD can remain fixed, and carry a fallback default value.
> 

In fact that the 'update string' method could eat up the boot time. 
Hence, the SMBIOS string patching is not prefered.

Regards,
Nhi


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