we have considered investing in making a good one, but it seems the industry trend has been to go away fast from > "raw" nand towards eMMC managed NAND..... and don't seem to have any > devices actually using this > > but UBI/UBIFS is not a bad solution in this space either... I would like to moderate that statement as most embedded devices will have some raw Flash (NOR or NAND) not only for the boot but for the information which requires very frequent update and long span life. The new generation of NAND Flash are getting so bad at keeping the data that soon we will have to consider them more, like a very slow refreshable RAM, than like a real Flash. On some new very high density NAND Flash type, the retention of data can go as short as 3 months just after a 1000 write cycle. On a Flash USB disk that might be acceptable but in a TV, who would like to get it's entire system wiped out after letting it 3 months off. I don't think it would be any better in a car ... On high read write usage (e.g. pause live TV application) most USB stick don't last 3 weeks (I have tested almost all fs known to Linux). Recent test on Flash drive with SATA interfaces have been similarly catastrophic. The current only, today available long term and reliable solution that I know, is either to use raw Flash with an adequate file system or a HDD. High cost SDD seem to fit the job but are out of scope from a price point of view.
The test done by my team show that you really want to test all your use cases very carefully before dumping the raw Flash from your design. This means that Flash file system will remain important to MeeGo for many years. This said, integration of Flash based file system is very easy. The TV product Cubovision shipped to Telecom Italia use MeeGo 1.0 and jffs2 and that did not present any special integration issue. yaffs2 has some license issue which makes it more difficult to integrate in your boot loader which often is also required for backup purposes. Addressing the issue of new generation of short term NAND Flash is a real need that will have to be managed, but at least, for the coming years, raw flash will remain inevitable in embedded devices and so including based support of jffs2 (or an equivalent which is license friendly with the boot loader requirement of static linking with proprietary code) would be a good idea. -- Dominig ar Foll MeeGo TV Open Source Technology Centre Intel SSG > > _______________________________________________ > MeeGo-dev mailing list > [email protected] > http://lists.meego.com/listinfo/meego-dev _______________________________________________ MeeGo-dev mailing list [email protected] http://lists.meego.com/listinfo/meego-dev http://wiki.meego.com/Mailing_list_guidelines
