Re: [Ipodlinux-devel] ipod reverse engineering

[Samuel O. <or...@fa...>]

Hi Bernard,

Thanks for the answer.
So you basically disassembled the firmware and poke around it, right ? 
I'll go the same way, then...
Another question: As far as I understand, the PP5002 is a dual ARM7 core 
chipset. By reading the current ipodlinux code, we just use one of this 
ARM7. I guess Apple firmware uses the second one as a dedicated audio 
decoding chip. If so, do you have any plans on trying to access both 
ARM7 too, and sticking a userland audio player to one of them ?

Cheers,
Samuel.


Bernard Leach wrote:

>Hi Samuel,
>
>the information on the PP5002 has been derived by reverse engineering the
>Apple firmware (and much experiment!).
>
>Some parts of the firmware are quite helpful in the reverse eng process, e.g.
>in the bootloader there are "command" functions with nice useage strings that
>implement things like "power down LCD", or sound piezo.  Other parts are not
>so helpful and brute force is the only technique.
>
>I have requested the development docs from PortalPlayer and although they said
>they would try and get them to me (without requiring a NDA) they never got
>around to it.
>
>cheers,
>bern.
>
>Samuel Ortiz <or...@fa...> said:
>
>  
>
>>Hi guys,
>>
>>I got a 2.4.24-uc0 + latest ipodlinux cvs booting on my 3G ipod this 
>>weekend. This is an impressive work !
>>I was even more impressed when I started to look at the code. IMHO, 
>>writing this code without documentation nor JTAG interface is not a 
>>piece of cake...
>>Since I now would like to contribute to this project, I need some kind 
>>of help. I am interested in adding some power management features to 
>>this kernel. Portalplayer claims that its chipset provides many power 
>>management hooks, but how can I get some informations about it, without 
>>having any useful PP5002 docs ?  More generally, how did you manage to 
>>reverse engineer this machine ? As an example, how did you manage to 
>>understand that, in order to set the CPU speed to 75 Mhz, you'd have to 
>>do this:
>>
>>    outl(0x02, 0xcf005008);
>>    outl(0x55, 0xcf00500c);
>>    outl(0x6000, 0xcf005010);
>>    outl(24, 0xcf005018);
>>    outl(75, 0xcf00501c);
>>
>>How did you know that you have to write to this specific ports ? Did you 
>>get all this information from Apple's firmware ?
>>
>>Thanks in advance for your time and answers !
>>
>>Cheers,
>>Samuel.
>>
>>
>>
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>>
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