RPDB/RPDS necessity for LPID==0

[Amol]

Hello,

The question I have has to do with the hw design of pwr9 radix mmu.

It seems (perhaps ignorantly so) to me that, for LPID==0, the mmu
doesn't need the partition-scoped radix tree, if PRTB were actually
a host real address.

But, for that partition, the PRTB is an effective address. The
parition-scoped radix tree is used for translating the PRTE's EA
to HRA.

What is the reason for not choosing to embed an HRA in PRTB
for that partition?

Thank you,
-amol