Root Nexus
The initial target chosen for the port of solaris was very close in architecture to an x86 having a similar Northbridge / Southbridge approach. This target uses a host processor approach. This fortunately allowed quite a bit of the existing x86 I/O source in solaris which is PCI based to be used with minor modifications.
The ODW utilizes the Marvell Discovery II MV64360 device which is designed for PowerPC processors such as the Motorola MPC74xx and MPC75x families and the IBM 750CXe/FX series CPUs. These devices support PowerPC processors and both the 60x and the advanced Motorola MPX bus protocols. The Marvell Discovery II MV6436x devices are the only system controllers to support Symmetrical Multi-Processing (SMP) in both 60x and MPX modes, enabling highest processor performance.
Going forward if more integrated SOC type processor is used ie: Freescale 8641 or 502 core based variant ie: EFIKA an updated root nexus driver will need to be composed.
The Root Nexus Overview is a good link in OpenSolaris to review.