General ARM/MiPS question: SATA Port Multipliers

I've read elsewhere that this question may be kind of stupid for embedded applications, BUT: do any ARM or MiPS SOCs that have SATA ports handle PMP port multipliers?

I've been seriously thinking about building a big near-line rack-mount NAS based around Tahoe-LAFS or similar where the main point is extreme energy efficiency and redundancy, where the drives AND controller(s) spend most of their time spun down--I freely admit I got the idea from Facebook's long term storage pods, which I don't have the link to at the moment.
Anyway, x86 is getting there, but ARM (and, to a lesser extent, MiPS) is king in this area, but I've read that not one of them support PMP. Is this true, and if so, is there hope this may be rectified in the future?

Related question: then what all those 4 or 8 port NASes use for controllers?

SATA PMP is a feature of the SATA controller and its driver, not the CPU architecture.

If a SATA controller chip supports PMP and the Linux driver for that controller knows how to use that feature, then a system using that chip will support PMP.