We have a client building a PPC8548-based product who insists that we allocate DRAM real address space in two large chunks at 0-2GB and 4-6GB in the 36-bit address space. It doesn't look like U-Boot's bd_info structure allows for that, and it doesn't look like the Linux init routines (which accesses the passed table) knows how to handle discontiguous memory either (as opposed to X86 Linux, which can accept an E820 table).
It looks like Linux cleans out the TLB's pretty quickly, so it wouldn't know the VA-to-RA mapping.
I've seen papers on some PPC Linuxes that handle large discontiguous real DRAM memory spaces, but it doesn't look like the Linux in ELDK does. Is that correct?
This is just the start of a headache between the architects and we poor implementers. It's not clear to us that, even with ATMU support, how normal drivers are going to know how to create real addresses for buffers and such to use when programming DMA controllers or external PCI devices.
Any comments would be VERY appreciated.
Regards, J