> > Yes, it's theoretically possible. It's not desirable.
> 
> Hm. I think it depends on how long the transition takes.
> If it could be done in short term, it is worse to make efforts for
> coexistence. But if it takes long time, coexistence is worth doing.
> 
> And from the observation of what FreeBSD does, I have the impression
> that it takes long time. For example, FreeBSD-3.0/pc98 is not much
> usable for now, because it lacks CAM based SCSI driver.

You may not have understood me. You can coexist but only in separately
configured/compiled kernels. That allows for you to select support for
platforms/HBAs that aren't yet supported with the new framework. I just
claim that it is not necessarily desirable to have to two support both
frameworks running in the same kernel at the same time.