Re: downloading elf file via JTAG

[Grant Edwards <grante at visi dot com>]

On Tue, Mar 13, 2001 at 10:08:02AM -0500, Fernando Nasser wrote:
> Grant Edwards wrote:
> > 
> > On Tue, Mar 13, 2001 at 07:41:05AM +0100, karsten@thebox-communications.de wrote:
> > 
> > > I have problem with downloading ELF files with Insight 5.0 via
> > > JEENI JTAG interface. I want to download a program that is
> > > linked for address 0x4000000 to another address than this,
> > > because at address 0x40000000 is in RAM and I want it in flash.
> > > A bootloader copies it on reset to 0x40000000. My problem is
> > > that Insight always loads the programm at that address for what
> > > it was compiled for.
> > > Can somebody tell me how I get the program downloaded via JTAG
> > > to another address than specified in the ELF file ?
> > 
> > Use objcopy.
> > 
> > The --change-addresses option, IIRC.
> 
> I guess what Grant is suggesting is:
> 
> 1) Make a copy of your object file that has the other (flash)
>    address using objcopy

> 2) Use GDB with this file to download the program to flash

I doubt that you can use GDB to download something to flash.
The Jeeni doesn't know that a particular region of memory is
flash and doesn't know the sequence required to write stuff
into flash.  I didn't understand that you wanted to use GDB to
write to flash -- what you asked was how to change the download
address.  That's easy.  Writing to flash is harder. ;)

If what you really want is to write something into flash,
you're going to have to write a program that knows about your
particular type of flash memory.  There are two ways of doing
this:

  1) Use GDB to download your application program (not the
     flash burner, what you want to end up in flash) into it's
     executution location in RAM.

     Download your flash burning application into another
     section of unused RAM.  Run the flash-burn program to copy
     contents of RAM into flash.

or  (this way is cooler)

  2) Link an image of the application program (as a block of
     data) with the flash-burning program.  Then just download
     the result using GDB and run it.

     There are various ways of getting the image of one program
     linked as a data block to another.  The easiest is to
     convert the "payload" program from ELF to binary format
     using objcopy.  Then convert it _back_ to ELF format
     (again using objcopy) specifying a unique section name
     (e.g. ".payload").

     In your linker script, suck in the .payload section from the
     file you just created and assign some symbols to the start
     and size of the .payload section so that the flash-burn app
     knows where to copy from.

     I generally specify the flash destination as a symbod
     defined at link time on the ld command line.

> 3) Exit GDB and reboot your system so the program gets loaded at
>    0x40000000
> 4) Start GDB with the original object file (that has 0x40000000 as load
>    addr)
> 5) Connect to the target and debug normally

-- 
Grant Edwards
grante@visi.com