Hi Ard,
On Sat, Nov 26, 2022 at 06:34 AM, Ard Biesheuvel wrote:

The remaining code still looks a bit clunky to me. Can't we just
return an error from the library constructor of the library cannot
initialize due to a missing prerequisite?

The problem with returning an error code from a library constructor is that it generates an ASSERT for debug builds. The reason is that the generated code in AutoGen.c looks as shown below:

VOID
EFIAPI
ProcessLibraryConstructorList (
IN EFI_HANDLE ImageHandle,
IN EFI_SYSTEM_TABLE *SystemTable
)
{
EFI_STATUS Status;

Status = HobLibConstructor (ImageHandle, SystemTable);
ASSERT_EFI_ERROR (Status);
...
Status = ArmTrngLibConstructor ();
ASSERT_RETURN_ERROR (Status);

}