After the recent US ruling which declared jailbreaking Apple devices to be legal, Nokia heads over at symbian-freaks have accelerated their efforts to create custom ROMs.
An user called fonix232 recently posted the following to the Symvian DevCo mailing list – it gives a nice overview and “history” of the recent happenings:
Hacking into the system is just a word for accessing the phone’s restricted areas (c:sysbin, c:private, etc) with a simple file browser. It can be done in many ways.
First, there was the HelloCarbide method. It was based on a system bug, what allowed to access any folder if a fie browser was running in the moment of bugabuse. So people did this, copied Z, and developed a method to install ANY software without the need of signing. That was done by modifying a value in InstallServer.exe, and then placing the modified executable in C:sysbin.
Nokia patched this on N95 V31, so we needed another way. The other way was to map C:sysbin as a different drive (yes it is possible on Symbian) and copy the executables and drivers of an application called ROMPatcher. This application does what it’s name says: applies patches on given areas of RAM. This made us possible to create mods on-the-go. No need for editing binaries anymore, but apply a patch, and it is already modified.
Nokia close this hole again, with firmware 5800 v40. Then, there were no holes. After a little time and lots of thinking, a team called PNHT grabbed my partial research on the Nokia Firmware Format (file extension FPSX), and based on it, with lot of help from an individual developer and modder Il.Socio, they made firmware editing possible for a few phones. This is an easy theory:
Nokia uses ROFS and ROM images in firmwares. ROM is for any base kernel executable – currently unmodifiable. ROFS1 is in CORE, just like ROM, and it contains a few stuff for ROM executables. ROFS2 contains languages, and other resources, like skins, and stuff. And finally, ROFS3 contains any carrier data. Now we have the possibility to edit ROFS2 and ROFS3, directly from the FPSX container. This way, we can integrate our favorite apps into our own custom firmwares, or set some options to other values by default, replace the base skin, port the Omnia HD’s homescreen, and such things.
So hacking is basically opening up the system for modding.
Not much more to add here…