I don't think you see my point here. Even with the PIC overclocked to 50MHz, I'm guessing you'll get to bash after like about 4 hours. What kind of an application are you exactly planning to do with that? He got the time, skills and effort to manage to boot linux on an AVR but I don't think that is anything more than proof of concept. If you want to use an OS on an mcu, there are many RTOS' out there suitable for the job. If you still want to boot linux on a PIC, a much better solution would be to compile the whole linux source for a PIC rather than emulating the ARM structure on a PIC. Obviously this would require much bigger effort to accomplish as there isn't any decent gcc style compiler for PICs and I don't know of any distro compiled with anything other than gcc (Clang maybe but that's still Utopia) let alone other problems one will encounter on the way. May I ask what is your intend for a PIC based linux?
I clearly understand what you are saying . I'm not at all focusing on linux. I given it just as an example. I just need to design an sbc which can run an os with gui support. I'm much better with pic than avr or arm that's why chosen pic. Can you please refer a good RTOS with GUI support.....