[ELDK] ELDK Linux 2.6.29, MPC885ADS and early console

[Sylvain ANDRE]

Hi Detlev,

I came back to my office this morning. I removed all my code from the 
Linux kernel as you said and tried again with Linux post mortem.
Here is the result :

<6>Using Freescale MPC885 ADS machine description.
<6>Using Freescale MPC885 ADS machine description.
<5>Linux version 2.6.29-rc7(root at localhost.localdomain) (gcc version 
4.2.2) #4 Mon May 4 09:25:51 CEST 2009

and nothing after (the previous error message disapeared).
But the console is still quiet.

    Cheers.
    Sylvain.


Detlev Zundel a écrit :
> Hi Sylvain,
>
>   
>> finally I succeeded with your recipe, here is the result of the memory
>> dump : (concatenated ASCII only)
>>
>> <6>Using Freescale MPC885 ADS machine description.
>> <6>Using Freescale MPC885 ADS machine description.
>> <5>Linux version 2.6.29-rc7 (root at localhost.localdomain) (gcc version
>> 4.2.2) #3 Fri Apr 17 09:30:49 CEST 2009.
>> <1>Unable................................................ess 0xff000ad8.
>> <................................................................s of
>> bad area, sig: 11 [#1].
>> <4>Freescale MPC885................inked in:.<4>NIP
>>
>>
>> 0xFF000AD8 is the physical address of PEDAT I/O register. I use it to
>> drive LEDs. Perhaps it's the reason since the beginning ...
>>     
>
> Yes indeed.  Did you really to simply write to those addresses?  This is
> bound to fail with (recent) Linux.  Remember that Linux uses the MMU and
> you cannot use physical addresses easily.  Usually you will want to do
> an "ioremap" for a physical address to install a translation and use the
> returned pointer.  But even this is not so easy very early in the Linux
> boot process as the memory management implementing "ioremap" also needs
> to initialize itself.
>
> So I'd propose to remove all your code from the Linux kernel and try
> again now that you know how to get to the contents of the Linux
> logbuffer.
>
> Cheers
>   Detlev
>
>