[coldfire-gnu-discuss] Debugging/Running program in internal Flash.

[Claude Sylvain]

Hello Nathan,


 >
 > Nathan Sidwell wrote:
 >
 >
 > Looking at the way the PC is behaving I think there's a cache problem.
 > The Icache has not been flushed and has something stale in it.  That
 > would explain why the pc has landed at 404, which is not an instruction
 > boundary.
 >
 > I'm not sure how that's happened.  IIUC you're using the m52235evb config,
 > right?
 > That does tell the sprite that there is a cache.

The target I use is the M52235EVB.

Sprite is launched using the following command:
	target remote | m68k-elf-sprite pe://USBMultilink m52235evb

I suppose that the command line parameter "m52235evb" refer to the
file "m52235evb.xml", located in "CodeSourcery\Sourcery 
G++\m68k-elf\lib\boards\".  This file seems to be the configuration 
file you talk about and seems to include something related to the 
cache.  See below the header of that file:

				   ----------

<?xml version="1.0"?>
<target-description>
   <target-features>
     <cache/>
   </target-features>

				   ----------


 >
 > Here are some suggestions:
 >
 > *) Reset or powercycle the board (the sprite should be resetting the
 > board on first connection though)
 >
 >
 > *) Force a write to RAM from gdb.  this will cause the sprite to flush
 > the Icache.
 >         p/x *(int *)__data_start  = 0x1234567
 >
 > then reset the pc to 0x400 as you have been doing, and try again.
 >

It is really strange, the symbol "__data_start" seems to not be
the start of the internal SRAM !?
Its value is 0xb5b88126 instead 0x20000000 (as defined in the linker 
script "m52235evb-rom.ld").

GDB can not write at such an address.

See the GDB output below:

				   ----------

..
m68k-elf-sprite:Opening P&E USBMultilink port 1 (USB1 : USB-ML-CF Rev 
C (PE60123
45))
m68k-elf-sprite:Target reset
0x00000000 in __interrupt_vector ()
(gdb) p/x *(int *)__data_start = 0x1234567
m68k-elf-sprite:Memory write verification failed; config file error?
Cannot access memory at address 0xb5b88126
(gdb) print (unsigned int *) __data_start
$1 = (unsigned int *) 0xb5b88126
(gdb)

				   ----------


I don't know a lot about GCC linker script file, but something seems 
to be strange to me.
The section that define __data_start in "m52235evb-rom.ld" linker 
script file is as follow:

				   ----------

   .data :
   {
     __data_load = LOADADDR (.data);
     __data_start = .;
     *(.got.plt) *(.got)
     *(.shdata)
     *(.data .data.*)
     *(.gnu.linkonce.d.*)
     . = ALIGN (4);
     _edata = .;
   } >ram AT>rom

				   ----------

What is the purpose of "AT>rom" ?
Maybe the problem is related to that instruction !?


Regards,

Claude Sylvain
Electro-Technica inc.