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diff --git a/doc/nokia-tips b/doc/nokia-tips new file mode 100644 index 0000000..468c1a1 --- /dev/null +++ b/doc/nokia-tips @@ -0,0 +1,105 @@ +<b>Nokia tips</b> + +When developing this tool I've found some bugs and misfeatures that +should be fixed to make flashing safer and cleaner. + +Before reading the list of the following items I would like to say that +Nokia has done a wonderful work on this device on the flashing/nolo parts, +it's really hard to break the device and it works pretty nice. BTW I +think that there are some things that should be fixed. + + +<b>*) Flashing at low battery level</b> + + When the device is under a certain limit of battery it will not start, + this is done by initfs, without any warning message or so, this really + scares end users, because the battery level check is done in the initfs + boot stage, not inside NOLO, so it's possible to flash the device on + low level batteries. + + This is *really* dangerous and not very user friendly. + + +<b>*) Internal nolo state not reset'd</b> + + It's possible to get nolo on a strange state that always returns error + when flashing pieces, it's mandatory to reboot the device to recover + the original nolo state and be able to flash again. + + This is an strange and not very clear to me. + + +<b>*) Buffer overflows</b> + + The original nokia flasher has some buffer overflow bugs that should + be fixed. They're safe for 99.9% of cases, but bofs on critical programs + like this one should not be there. + + If nokia releases the source of the flasher it would be easier to make it + better and safer. BTW the original flasher is much more secure and reliable + than this one. + + +<b>*) Missing stuff</b> + + There are some flashing options that are not working like passing arguments + to the kernel, set the hw revision or do a cold flash (the most critical + part is undocumented). + + +<b>*) Weird firmware format</b> + + The (new and old) FIASCO firmware format is not a very clean format, it + doesn't provide any checksumming facility to ensure that the contents of + the firmware have been modified or incorrect, so i'll rather encourage + to design and create a standard firmware format for embedded devices with + checksumming, signatures, handling libraries, documentation and so. + + I'll happilly collaborate on the design of this open firmware format, and + it would be used on all the open source-based devices to aim interoperability + between devices and flashers, providing a more standard and reliable way of + flashing devices. + + This will ease the development on new devices, so the information and the + code could be revised and enhaced by zillions of eyes. + + +<b>*) Poor checksumming</b> + + The only checksum is a 16 bit xor of the whole firmware piece and it's only + checked after sending the piece to the device. + + This is not very safe, because 16 bit checksum is a very low-quality + algorithm. It currently performs a unique check at the end, it could be + better to check each data block to avoid errors or invalid flashing, isn't it ? + +<b>*) No validation of pieces before flashing</b> + + I've implemented a minimal check of the pieces to avoid flashing invalid + pieces on the wrong place. This is done in fpid.c (firmware piece identifier). + + This should avoid end users to flash initfs on the kernel or weird things + that can (pseudo)brick the device. + + +<b>*) Reverse flashing</b> + + If you want to test a new firmware, but you don't want to loose all the + contents of your device. The only way to do that (afaik) is from the + device. That's done with `0xFFFF -e [path]`. + + IMHO the reverse flashing (dump) should be implemented inside the bootloader + (NOLO in this case), and allow to retrieve (at least) the most critical + pieces of the firmware before flashing a new ones, and restore them in + case of a wrong checksumming (for example) + + +<b>*) Documentation</b> + + The nokia flasher comes as is, without documentation. This is not good + to anybody, because the lack of information is always the root of problems, + fear and ignorance. + + So giving a minimal documentation about how to use the flasher (not only + the basic usage stuff (like the maemo community has done in the wiki) + would be good for everybody. |