RE: [microblaze-uclinux] Newbie question about external ram executability

["Kevin Somervill" <kevin.m.somervill@xxxxxxxx>]

Hello Wade. 

|   That 'brild r9, r15' was in the code loaded into BRAM, and it was
| telling me through the debugger that it was getting ready to 
| execute at
| address 0x80000000.  I'm beginning to suspect the mdm does 
| not work with
| external ram at all, since the gdb totally blanked the screen when it
| should
| have been showing me the code.

The mdm does work with external ram, I've used it.  I have not however used
gdb that I can remember so I'm not much help there.

| |   I downloaded the program into external static ram at 
| 0x80000000 and
| | verified it was there.

This should prove that mdm works with external ram.

|   I also tried the relocation trick, and when you do that, 
| mb-objcopy fails
| dramatically whe
| converting to binary.

It's not a trick, the code must know where it is.  You have to set the start
address. Anyone please correct me here if I'm wrong, but I'm pretty sure
that's the deal.

|  It gives 'BFD: Warning: Writing section '.text' to huge (ie 
| negative) file
| offset 0x80000000.'
|  This repeats for every section, then it says 'mb-objcopy: 
| test.bin: File
| truncated' and produces
| a 40 byte file from a file that is around 1,000 bytes in size.

I've done exactly what you are doing (though 18 months or more ago) and it
sort of just worked.  I don't remember having to do mb-objcopy.  I could
swear I just dow'ed an elf file.  If I had time, I'd throw something
togethher and test it, but it certainly won't happen this week.  Sorry.

But to back up a bit. 
1. You can read and write 1-byte, 2-byte, and 4-byte data from and to your
external memory.

2. You can download your program to your memory and view it.  
    - Did you look through the disassembled downloaded instructions to
verify they are targetting the correct address range (life at the
0x80000000)?

3. Can you 'con' a small program in external memory (blink an led or
something)?
    - Unless you can do this, jumping to your code won't help.

Good luck,
./ks


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