I and my Friends have been trying to custom build a mid-range mobile phone. We are thinking of porting linux to it and modify it as per our requirements.
Now, The problem is that we are unable to decide about which processor to use - weather to use ARM or any other and if ARM then which ARM architecture. It would be great if someone could also suggest which linux variant to port.
OUR AIM: We want to build a device in this category, please please follow the link: Please Click here
Please give your valuable inputs, it will help a great deal to us youngsters.
Thanks and Regards, Avi and Co
Are you seriously getting into the phone business or is there some other real goal you are after (learning how something works, wanting to create a phone user interface, etc)? Getting into the phone business means tens to hundreds of millions of dollars, per product, of development money. Armies of lawyers to figure out the dozens of companies you are going to have to pay patent royalties to (do you follow slashdot.org?), etc. With that budget you already have the money to buy each of the popular eval boards and try them out. Likewise the software staff to try each of the linux porting methods.
Not to completely discourage you though.
ARM makes processor cores, but not chips. Other companies take an ARM core, wrap it with something interesting and sell that chip as a product. There are many websites that show the deconstruction/disassembly of quite a few phones and other products. You need to research this, I would be surprised, but if there are phones that use commercially available processors, those are the chips you should look for. I suspect most are going to be custom made for that phone or phone vendor and you are likely not going to be able to even get a datasheet much less a way to buy them on a board (other than buying a phone of course).
ARM is a very good choice for phones, there are many good reasons why ARM is used in phones and most other handheld devices. Go to ARM's website and look at the cores availble. Compare that to what websites claim phones or other similar devices (ipad, kindle, nook) are using. Then search around for companies that have chips with those cores. You will probably just end up looking at the ti omap or the marvell chip in the openrd or plug computer (I dont know its name/model off hand, kirkwood or something like that). The nvidia tegra is the hot new chip for phones, I think they have an eval board.
If you have not already ported linux to ARM then I would actually suggest working on that against QEMU, and wait on purchasing any hardware. As already mentioned a little googling goes a long way. You can even create and test your phone user interface software without needing to purchase any hardware. By surfing around getting a feel for what lcd panels, etc are used by various vendors you can get a feel for what your software is going to be limited to or have to do. It wont cost you anything but time to figure out what you do and dont want or will or wont support without having to spend any money on hardware.
I would compile everything for a generic arm at first (armv4 for example) and worry about tuning for the particular core later, if at all. Sure, ultimately you are going to need to get a feel for the performance of that core and caches and mmu, etc. worry about that later you have a lot of research to do and software ground work first. If you must get a beagleboard or openrd (with all the extras you have to buy to make a beagleboard usable/useful, the openrd is cheaper, faster, etc). (avoid the plug computer, doesnt fit with what you are trying to do anyway).
There are many good reasons why linux is not used on phones, so you need to research that as well and decide if that is the path you really want to take.
You are likely going to end up with an mpcore or cortex-Asomething. So the ti opap, nvidia tegra, marvell sheeva, etc, all fall into that category. You can get the feel for a cortex A series from any one of them.