Mark Pilant wrote:
Hi Andy.
Finally, I notice there is one area of memory, defined at 0x70000000, which has a TLB but does not appear to have any real memory to back it up. (This address is associated with the CFG_INIT_RAM_ADDR defined symbol.)
This is just the initial area to store stuff before RAM is actually set up. It has to be somewhere with nothing behind it so it will just stay in the cache. Most 85xx systems use 0xe4010000. However, once RAM is set up, this address loses its meaning
OK. That sounds reasonable, although I haven't run across this before.
I am hoping someone might be able to point out if I am missing something (subtle or obvious :-).
I had thought this might be the source of the CPM SCC problem I am having, but so far it does not seem to be the case.
I don't recall seeing the email about your problem. Could you redescribe it?
Simply put, I'm trying to get U-Boot 1.2.0 compiled and running on a Wind River SBC8560 board we have. From what I saw of the '8560 support in general and the SBC8560 in particular, I thought it would be relatively simple.
After setting up the ELDK on a Fedora Core 6 system I have, I was able to make a couple of changes to sbc8560.h (mostly to use SCC1 for the console) and build an image.
Loading the image into flash (using WR visionCLICK) everything goes along fine until the code attempts to initialize the CPM SCC Tx & Tx. After writing the appropriate value to the proper location, the code hangs waiting for the command to complete.
In reality, what appears to be happening is the code is reading one value (0x00810000) from the CPM CPCR (0xff7919c0) and if I dump that location using visionCLICK I see a different value (0x00800000). The difference being the code sees the busy FLG and dumping the location has it clear; indicating it is no longer busy.
This feels a lot like a caching issue, but from everything I can see, the TLB is set up with the cache inhibited, so everything should be read/written through to memory.
Another possibility is that the register is missing the "volatile" qualifier and thus the compiler is not re-reading the register every time around the loop. If this is a possiblility, disassemble the routine and see what the compiler actually produced.
I have been trying for about the past two weeks to sort this out and get U-Boot up. I'm not worried about the Linux kernel right now :-)
- Mark
Good luck, gvb
Due to idiotic lawyer wanabes, in one second this email will self-destr%^*-.