Re: [edk2-devel] [PATCH edk2-platforms 1/1] SbsaQemu: use FEAT_RNG for EFI_RNG_PROTOCOL

["Leif Lindholm" <quic_llindhol@quicinc.com>]

On 2024-07-01 14:35, Ard Biesheuvel wrote:
>> Ard: would you be opposed to putting a DEBUG print and/or an ASSERT in
>> BaseRngLibContructor if mRndrSupported == 0?
>>
>> An alternative would be to place a test and noisy warning inside
>> SbsaQemuPlatformDxe.
> 
> I'm not sure I follow what we are trying to fix here. RngDxe will
> simply not load if BaseRngLib does not find FEAT_RNG support.
>
> If the issue is other, existing users of RngLib that are currently
> served by BaseRngTimerLib, we could make the library class resolutions
> introduced here local the RngDxe driver, using
> 
> SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.inf {
>    <LibraryClasses>
>      RngLib|MdePkg/Library/BaseRngLib/BaseRngLib.inf
>      ArmTrngLib|ArmPkg/Library/ArmTrngLib/ArmTrngLib.inf
>      ArmMonitorLib|ArmPkg/Library/ArmMonitorLib/ArmMonitorLib.inf
> }

Good point.

I think Ard's example solves the original purpose (providing 
EFI_RNG_PROTOCOL to linux efi stub) while not breaking any potential 
usage before this point.

I'd still quite like to nudge existing users onto a more recent cpu,
with less cryptic console output. But if we do the above we can drop the 
conditional part and just put a test and a message in the PlatformDxe.

(And have the commit message be clear on RngDxe being added.)

/
     Leif



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