[okl4-developer] More NSLU2 debugging

[Joshua Root]

Geoffrey Lee wrote:
> On Sun, Jun 22, 2008 at 07:42:35PM +1000, Joshua Root wrote:
>> So you'd expect something like:
>>
>> add_mapping_init( kspace_phys, (addr_t)(XSCALE_DEV_PHYS+CONSOLE_OFFSET),  
>> (addr_t)(XSCALE_DEV_PHYS+CONSOLE_OFFSET), uncached );
>>
>> to work if I do it at the same time as the other 1:1 mappings? And after  
>> VM is turned on here (init.cc:353):
>>
>> /* Enable virtual memory, caching etc */
>>     write_cp15_register(C15_control, C15_CRm_default,
>>                     C15_OP2_default, C15_CONTROL_KERNEL);
>>
>> I should be able to write to the UART, yes? (And indeed I can in the  
>> simulator...) I've been doing pretty much what you suggest to pinpoint  
>> where it's failing, but I can't get any output after that  
>> write_cp15_register call. Could kspace_phys be constructed incorrectly?
> 
> Yes, I guess something hasn't been constructed properly.  I think if
> you turn off the MMU initialization you will actually get a bit 
> further - not saying that is the way to move forward, just that
> it properly is something that got put into the cpu which it didn't
> like.
> 
> It might be a good idea to print out the contents of physbase to double
> check that it's been patched properly, and also the contents of the
> page table etc that you write to the hardware.

Good call. Turns out that the physbase pointer that's passed to 
init_memory is null. I guess this means that the build system is failing 
to set __phys_addr_ram?

- Josh