Hi Liming,
I agree with the need for both packages. We should wait at least another day for any additional feedback on the package name GenericBoardPkg. That name may give the impression the package can generically be used on various boards whereas the intent here is a package containing common or supporting board functionality. An alternative name to consider is BoardSupportPkg.
As a reminder, ensure the separation of content follows 8.1 (or update the document if necessary):
Thanks,
Michael