NokiaCooker
NokiaCooker was a desktop program, described by its own page as "reserved to the Cookers", which allowed the files that make up a phone's firmware to be modified in order to produce customised firmware versions — known in that community as cooked firmware.
Archive notice. Symbian Toys was an independent hobbyist software project for the Symbian Series 60 platform, which Nokia discontinued in 2013. These pages preserve the project's own documentation as it was published. The software is no longer distributed here, and no support was ever offered for it. Device and platform names appear for identification only; the project was never affiliated with, endorsed by or connected to any device manufacturer.
What it could and could not touch
The scope was stated precisely, and the precision was the point. NokiaCooker could modify data located in:
- UDA — the user data area.
- ROFS — the read-only file system layers.
- ROFx — the additional read-only layers stacked above them.
It could not modify data located in the CORE. The page said "yet", which in practice meant never.
The warning, preserved as written
Not all the ROFS/ROFx can be modded. Modding a protected ROFS/ROFx you'll risk to brick the phone. If you aren't sure that your ROFS/ROFx can be modded, don't do it. The modding of the UDA, instead, is always a safe operation.
This warning is restored verbatim because it is the most useful sentence on the original page. The layered structure of a Symbian firmware image meant that some layers carried integrity protection and some did not, and the consequence of guessing wrongly was an unbootable handset. The safe operation — editing the user data area, which held preinstalled applications, wallpapers, ringtones and operator additions — covered most of what people actually wanted to change.
Change-log
From the BETA 0.6 build:
- New: a smart CRC fixer was added, so there would be no more CRC warnings in the flashing tool.
- Improved: the checkbox for ROFS resize was replaced with a button.
- Improved: slight interface improvements.
- Improved: better performance when showing folders containing a large number of files.
The CRC fixer is the interesting entry. Editing a read-only layer invalidates its checksum, and the flashing software then complains; recomputing the checksum after the edit turned a warning-strewn process into a clean one, and it is exactly the sort of small, unglamorous fix that made a hobby tool usable.
Standing terms
As with everything the project published, NokiaCooker came "as is" and, in the page's own emphasis, without any technical support. The author's position was blunt and consistent across the catalogue: anyone who did not know how to install or use the software probably did not need it.
Version history
Ten NokiaCooker builds are evidenced in the site's download records: beta 0.8, then 1.1, 2.02, 2.1, 2.2, 2.3, 2.9, 3.0, 3.3 and 3.4. Version 3.4 is the last one archived, and it is also the last release of any Symbian Toys program to appear in the record. The full inventory is on the release archive page, and the source was published in 2021 as the NokiaCooker source repository.
Related tools
The usual working order was to obtain an image with NaviFirm+, modify it with NokiaCooker, and — for changes that had to happen on a running device rather than in the image — apply patches at runtime with RomPatcher+.
What "cooking" actually produced
A Symbian firmware image was not a single blob. It was a stack: a core partition holding the operating system, one or more read-only file system layers above it carrying applications and resources, and a user data area holding everything a network operator or manufacturer wanted preinstalled but not fused into the system. The layers were assembled at boot into a single visible file system, which is why an application could sit in a read-only layer and appear alongside one the user had installed themselves.
A cooked firmware was a rebuild of that stack with the upper layers altered — unwanted preinstalled applications taken out, wanted ones put in, resources and branding replaced, occasionally a language pack swapped for another. The core stayed untouched, both because NokiaCooker could not modify it and because doing so would have taken the image outside anything the flashing tools would accept.
The reason people did this at all was that the alternative was living with whatever a market or an operator had decided a handset should contain, on a device with a very small amount of storage. Removing preinstalled software that could not be uninstalled was, for a lot of users, the entire motivation — the same problem IconHider later solved without touching the firmware at all.