Hi all,
I'm working on an AMCC PPC440EPx-based platform that's similar to the Sequoia. The board runs pretty well, but occasionally takes exceptions both in U-Boot and while running Linux. The exceptions vary from Illegal Instructions to FP Unavailable to FP Unimplemented to ITLB and DTLB Errors, to DSI, etc., which made us believe there's a problem with SDRAM. Sometimes there are simple hard lockups from which even the JTAG can't regain control. However, the SDRAM physical/electrical and DDR Controller configurations have been investigated in detail (and some corrections made) with no resulting improvement in the exception behavior.
We see problems primarily at 667 MHz but have noted some issues at 533 MHz as well. Some boards seem particularly susceptible to this while others rarely (if ever) exhibit the problem.
At this point all possibilities are on the table and I'm looking for any input from anyone with experience (good, bad, or whatever) with this processor and/or designs similar to the Sequoia.
Thanks very much, Dave