[U-Boot] MMU/PPC question

[SortaSBS Guy]

    I'm working on a u-boot port to custom hardware based on the Lite5200B board, with a MPC5200 processor. u-boot is working great (can boot from 16-bit flash, SDRAM is working and I can boot linux!) but now I'm working through some MMU configuration issues, and had a few general questions:

1. Does u-boot/linux make any assumptions about how particular BAT registers are used? For example, we're not using PCI, and I was going to use those BAT registers to cover some memory-mapped peripheral I/O space (ex: icecube.c, DBAT3 and 4 are used for PCI, so I would use them instead for our I/O ranges.)
2. Do you need a separate BAT register for each memory mapped I/O space? We have 4 chip selects, but could I arrange the chip selects to use a contiguous range and presumably cover that with a single BAT register? 
3. Would I need separate BAT registers for 8-bit vs. 16-bit devices?

    Also, maybe slightly off topic, but has anyone had problems using 8-bit peripherals on the MPC52000 in large flash mode? I'm seeing some odd behavior that looks as though the internal PPC bus thinks 8-bit data is on bits 8-15 and only ever reads/writes zeros, and the external data lines (d0-d7) show correct data for reads, and only shows correct data for odd-address writes.

   Thanks,