I'm trying to get u-boot version 1.3.4 working a custom MPC8548 based board (version 1.1.4 currently works fine on this board so the hardware is known to be good). I'm encountering the following problem during the early stages of the u-boot initialization and any insights as to what the problem may be would be greatly appreciated:
I have a BDI3000 and i'm using gdb for debug sessions. I started with the MPC8548CDS.h as my template for the build configuration file for this board.
1) in the start.S file the L1 DCache is configured to be used for initial RAM, this occurs in the code at the 'switch_as:' label. I set the CFG_INIT_RAM_ADDR to the value 0xd8010000 and this value is used to configure the L1CFG0 register. 2) execution soon jumps to the '_start_cont:' label and the stack is set up in this initial RAM area 3) I set a breakpoint at '_start_cont' and tried to examine the initial RAM memory with the gdb 'x' command: (gdb) x/16x 0xd8010000 0xd8010000: Cannot access memory at address 0xd8010000
So at this point should gdb be able to examine this memory area?
I compared the code in start.S for 1.3.4 with the code from 1.1.4 and although not identical the instructions to setup the L1 cache and use it for initial RAM end up using the same values and doing the same operations...
I can continue to execute code and soon we jump into the c routines where the global data pointer is initialized, attempts to display this gd_t structure give the same error message (no surprise there), so I'm guessing this structure does not get initialized properly and function using it read bogus values...
but I can continue stepping thru the initialzation functions, and for example when the console is initialized a long string of garbage shows up in the console terminal window, the baudrate comes from the gd_t struct so its not what I configured...
so i think this is close to working but something seems broken with using the L1 Dcache for initial ram...
thanks in advance for any ideas and suggestion and please let me know if there is additional info that might be useful for you to understand the problem...
davis mcpherson