[U-Boot-Users] Difficulty with symbol maps.

[Wolfgang Denk]

Dear Mark,

in message <9901EE1E8F8BD3119109009027A1B5F596AE38 at DIGINET2> you wrote:
> 
> I have built u-boot for an ep8260 & my custom target such that the code
> lives 
> in flash memory at 0xFF000000. However the reset configuration word is 

Are you sure? From what's printed below  it  looks  as  if  this  was
0xFE000000   instead.   What  is  the  value  of  TEXT_BASE  in  your
"board/ep8260/config.mk" file?

> programmed to initialise flash at address 0x00000000. This appears to work
> ok 
> as the board does indeed boot correctly. However I would like to be able to 
> step through the code using a BDI2000. 

Should be no problem.

> When I attempt to load the symbol file into gdb at address 0x00000000, the 
> symbol _start which I expected to reside at 0x100 actually resides at
> address 
> 0xFE000100 as illustrated in the following trace.

> $ ppc-linux-gdb
> GNU gdb 5.1.1
> Copyright 2002 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and you are
> welcome to change it and/or distribute copies of it under certain
> conditions.
> Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB.  Type "show warranty" for details.
> This GDB was configured as "--host=i386-redhat-linux --target=ppc-linux".
> (gdb) bdi
> 0x00000100 in ?? ()
> (gdb) add-symbol-file u
> u-boot       u-boot.bin   u-boot.map   u-boot.srec
> (gdb) add-symbol-file u-boot 0x00000000
> add symbol table from file "u-boot" at
>         .text_addr = 0x0
> (y or n) y
> Reading symbols from u-boot...done.
> (gdb) info address _start
> Symbol "_start" is at 0xfe000100 in a file compiled without debugging.
> (gdb)
> 
> Interestingly, when I attempt to load the symbol map at any other address 
> than zero the symbols appear fine. 
> 
> Any ideas or thoughts would be appreciated.

I think you found a bug in GDB. I see the same problem when trying to
load the symbol table at 0:

-> ppc_8xx-gdb      
GNU gdb 5.1.1
Copyright 2002 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "--host=i386-redhat-linux --target=ppc-linux".
(gdb) add-symbol-file u-boot 0x00000000
add symbol table from file "u-boot" at
        .text_addr = 0x0
(y or n) y
Reading symbols from u-boot...done.
(gdb) p _start
Cannot access memory at address 0x80000100
(gdb) p &_start
$1 = (<text variable, no debug info> *) 0x80000100 <_start>
(gdb) symbol-file 
Discard symbol table from `current image(s)'? (y or n) y
No symbol file now.
(gdb) add-symbol-file u-boot 
add symbol table from file "u-boot" at
(y or n) y
Reading symbols from u-boot...done.
(gdb) p &_start
$1 = (<text variable, no debug info> *) 0x40000100 <_start>
(gdb) symbol-file 
Discard symbol table from `current image(s)'? (y or n) y
No symbol file now.
(gdb) add-symbol-file u-boot 0x10000000
add symbol table from file "u-boot" at
        .text_addr = 0x10000000
(y or n) y
Reading symbols from u-boot...done.
(gdb) p &_start
$1 = (<text variable, no debug info> *) 0x10000100 <_start>
(gdb) 




Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
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